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The No. 10 recovery boiler for Tomioka Mill was completed in May 1990 and KP plant No. 3 which was completed in August 1990.This boiler is a higher pressure, temperature, thermal efficiency and low pollutants emission recovery boiler of the largest class in Japan. 50% of the steam requirement in Tomioka Mill is produced by this boiler.At the first stage, the plugging that was characteristic of kraft recovery boilers occured in the supperheater and the evaporator. For the past two years, we have doing monthly burning tests of black liquor fuel.Now, with the experience of two years operation, we have improved the operation method of this recovery boiler. The following is the report of the No. 10 boilers operation.

4 páginas, 5 figuras.-- PACS numbers: 82.37.Vb, 81.05.U-, 81.07.De, 82.50.-m, We show by first-principles simulations that ultrafast laser pulses induce different chemical reactions in a molecule trapped inside a nanotube. A strong laser pulse polarized perpendicular to the tube axis induces a giant bond stretch of an encapsulated HCl molecule in semiconducting carbon nanotube or in a BN nanotube. Depending on the initial orientation of the HCl molecule, the subsequent laser-induced dynamics is different: either complete disintegration or rebonding of the HCl molecule. Radial motion of the nanotube is always observed and a vacancy appears on the tube wall when the HCl is perpendicular to the tube axis. Those results are important to analyze confined nanochemistry and to manipulate molecules and nanostructures encapsulated in organic and inorganic nanotubes., Y.M. is supported by the Next Generation Supercomputing project conducted by MEXT Japan. H. Z. acknowledges financial support from the National Natural Science Foundation of China (NSFC, Grants No. 11074176 and No. 10676025), the NSAF (Grant No. 10976019), and the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100181110080). A. R. acknowledges financial support from Spanish MEC (FIS2007-65702-C02-01), ACIPromociona (ACI2009-1036), ‘‘Grupos Consolidados UPV/EHU del Gobierno Vasco’’ (IT-319-07), the European Union through the FP7 e-I3 ETSF (Contract No. 211956), and THEMA (Contract No. 228539) projects.

We propose to use ultrashort laser pulses to detach intact graphene monolayers from a graphite surface, one at a time. As suggested by a combination of real-time ab initio time-dependent density functional calculations for electrons with molecular dynamics simulations for ions, this athermal exfoliation process follows exposure to femtosecond laser pulses with a wavelength of 800 nm and the full width at half maximum (FWHM) of 45 fs. Shorter pulses (FWHM=10 fs) with the same wavelength and intensity speed up the exfoliation and cause transient contraction in subsurface layers. Photoexfoliation should be capable of producing intact graphene monolayers free of contaminants and defects at a high rate.

Simulated scanning-tunneling-microscopy (STM) images of stable and metastable adsorption sites for the O atom on the Si(100) surface have been obtained by first-principles electronic-structure calculations within the local-density approximation. In the simulated STM images of both sites, the positions of O atoms are not seen directly, while the neighboring Si atoms are found to become bright spots. As for the metastable site, the bright spot originating from the surface Si atom moves when the polarity of the tip's voltage is reversed. This phenomenon is due to the electrostatic field of negatively charged O atoms

We report microscopic total-energy electronic-structure calculations which provide the cohesion mechanism and the energy-band structures of new forms of solid carbon, C60 and related materials. We find that C60, clusters are condensed via van der Waals-like forces and the resulting face centered cubic C60, is a semiconductor with an energy gap of ≈ 1.5 eV. Both the valence-band top and the conduction-band bottom are at the zone boundary (X point), but rotation of the C60 clusters modifies the energy-band dispersion. We also find that alkali-atom doping transforms solid C60, into a strongly bonded ionic metal in which both Madelung and band energies contribute to its cohesion. The overall structure of the calculated density of states is in excellent agreement with the photoemission, inverse photoemission and X-ray emission data for both pristine and alkali-doped fullendes. A unique linear relation between the superconducting transition temperature and the Fermi-level density-of-states over a wide range of temperature is found for potassium-doped and rubidium-doped C60, under pressure. We predict that the high electronegativity of C60 hinders the hole injection with halogen-atom doping. Finally, systematic calculations for carbon micro-tubules have been performed using a realistic tight binding model. We find that micro-tubules exhibit a striking variation in electronic conduction, from a metal to narrow-gap and wide-gap semiconductors, depending on the diameter and the degree of helical arrangement of the tubule.

The authors calculated the electronic structure of fullerenes, C60, C70, C76 and C84 by using the density-functional theory (DFT) or the realistic tight-binding model. C60K and C60Cl where K and Cl are trapped inside C60, are also studied. Results are discussed from the viewpoint of the fullerenes as 'artificial atoms', a spherical quantum system which one can modify and make use of to construct new materials. They also report the electronic structure of solid fullerenes: pristine FCC C60, FCC C60K, and FCC BC59 (one of the sixty C atoms in each C60 is replaced by B), and fullerides: KNC60(N=1-3) and C60Br (K and Br atoms are on the interstitial sites of the C60 lattice), obtained by the DFT.

We have theoretically investigated the possibility of halogen doping in solid buck- minsterfullerene ( C 60 ), assuming that the face-centered cubic lattice structure is unchanged by doping. Based on the first principles total-energy calculations, we have found that bromine atoms are exothermically incorporated into solid C 60 , but that hole injection in the valence band of the pristine C 60 is not achieved. Instead, we have found that new states consisting mainly of the bromine 4 p orbitals appear in the midgap of C 60 . Since these states are partially filled by electrons, it results in a metallic state. However, the band dispersion is very small so that the electron correlation might play an essential role. In that case a possibility of the Mott insulator may appear.

Fabrication of n-type diamond was studied by performing extensive first-principles total-energy calculations for a number of possible configurations during the epitaxial growth process. We find that spatially correlated codopant N–Al–N, which acts as a shallow donor in diamond, can be effectively formed by using a surfactant-based growth technique. This technique takes advantage of the difference in the growth modes of diamond which depend on surface species: incorporation of carbon into diamond crystal is promoted by surfactants (Al) but is locally prohibited by surface co-dopants (N–Al–N). Thus, the co-dopants are selectively buried in diamond. This approach provides a possible and very effective way to realize dense n-type doping of diamond which has not been possible using conventional techniques.

We show that the barrier profile of in situ grown AlOx tunnel barriers strongly depends on the material choices of the oxide-metal interface. By doing transport measurements on Al and Nb-based metal-oxide-metal tunnel junctions in a wide temperature range and using the phenomenological Simmons' model, we obtain barrier parameters that are qualitatively consistent with the values obtained from the first-principles calculations. The latter suggest that the formation of metal-induced gap states originating from the hybridization between the metallic bands and Al2O3 conduction band is responsible for the tunnel barrier modification. These findings are important for nanoelectronic devices containing tunnel junctions with a thin insulating layer.

We investigated possible sources of defect-induced magnetic ordering in carbon-irradiated graphite from first-principles calculations. Among candidate structures with interstitial defect configurations that could be generated during carbon irradiation processes, two metastable configurations with finite magnetic moments were identified. They are coupled ferromagnetically to their neighboring defects, thereby enabling them to contribute to the observed macroscopic magnetic ordering. The Ruderman-Kittel-Kasuya-Yosida interaction is considered as a possible mechanism for the ferromagnetic ordering.

The effect of growth hormone (GH) on immune function was studied using normal and hypophysectomised male Wistar rats. Hypophysectomy was performed by the auditory approach at 4 weeks of age. Normal and hypophysectomised rats were treated with saline or 0.4IU/body GH daily during 7 to 11 weeks of age. Histological features of the thymus and spleen and immunological parameters including blood cell counts, lymphocyte subsets, serum immunoglobulin levels, splenic natural killer activity, and mitogen-induced splenic lymphocyte proliferation were examined in the rats at 11 weeks of age. In hypophysectomised rats, the counts of peripheral white blood cells (5,513 +/- 813/microliters), lymphocytes (4,838 +/- 737/microliters), Th/i cells (2,237 +/- 329/microliters), and B cells (1,400 +/- 509/microliters), Th/i/Ts/c ratio (1.78 +/- 0.27), splenic T cell subsets (pan T: 51.0 +/- 4.3%, Th/i: 31.6 +/- 3.0%, Ts/c: 23.9 +/- 2.7%), and serum IgG level (2,148 +/- 470mg/l) were significantly decreased as compared with normal rats. Natural killer activity (17.8 +/- 4.6%) and mitogen-induced proliferation of T cells (Con A: 47.1 +/- 15.7, PHA: 51.6 +/- 12.5) were also suppressed. Hypoplasia of the thymus and spleen was observed in parallel to retarded growth of the rats. In contrast, GH supplement to the hypophysectomised rats resulted in increases in growth and lymphoid tissue, and the restoration of the counts of peripheral white blood cells (6,850 +/- 840/microliters), lymphocytes (6,211 +/- 731/microliters), Th/i cells (2,909 +/- 304/microliters), and B cells (1,947 +/- 402/microliters), Th/i/Ts/c ratio (2.04 +/- 0.34), serum IgG level (3,414 +/- 1,326mg/l), and natural killer activity (25.7 +/- 4.7%). However, splenic lymphocyte subsets and mitogen-induced proliferation of T cells were not recovered by GH treatment for 4 weeks. GH administered to normal rats increased serum IgG level (4,982 +/- 1,496mg/l) but did not affect other immunological parameters. These results indicate that humoral and cell-mediated immune function are impaired in hypophysectomised rats, but GH supplement administered to them restored most of the impaired immune function, suggesting that GH plays an important role in the development of immune function.

Photoassisted reactivation of H-passivated Si donors in GaAs has been demonstrated by first-principles calculations. In order to examine the survival of the excited state, we have applied our recently developed scheme of the ab initio molecular dynamics coupled with the time-dependent Schrodinger equation for electrons. We have found a possible electronic excitation which significantly lowers the dissociation-barrier height from 1.79 to 0.23 eV. This result explains well the recent experiment of carrier recovery by laser illumination [D. Loridant-Bernard, S. Meziere, M. Constant, N. Dupuy, B. Sombret, and J. Chevallier, Appl. Phys. Lett. 73, 644 (1998)].

Using a transmission electron microscope and a nanomanipulator, we explored the early head-to-head coalescence of two capped carbon nanotubes (CNTs) under induction of electric current. We measured detaching forces for coalesced CNTs, showing discrete identifiable values attributable to van der Waals interaction, single $s{p}^{2}$-like bonds, and double $s{p}^{3}$-like bonds by comparing them with forces obtained using molecular dynamics simulations. Our results underscore the feasibility of atomically controlled junctions of CNTs tuned by the amount of the electrical current.

In this paper, the numerical stability of simulations of the real-time propagation of electron wave functions under dynamical external fields is shown within the framework of the time-dependent density functional theory (TDDFT) by using periodic boundary conditions. The plane-wave basis set is used to express valence wave functions and fast Fourier transformation is used to treat differential terms in the Schr\"odinger (Kohn-Sham) and Poisson equations. The Suzuki-Trotter formula is applied for expressing time propagation of electron wave functions. An energy conservation rule for conditions with ions in motion and with a time-varying external dielectric field is shown, and numerical stability that satisfies this conservation rule is demonstrated. This will be a benchmark in developing a simulation with the use of other TDDFT schemes different from the current one, such as the real-space method.

A density functional technique for calculating interactions between highly charged ions and solids is presented, and the application of this technique to the simulation of an ${\mathrm{Ar}}^{7+}$ ion passing through a graphene sheet is demonstrated. The simulation is initiated with electronic states obtained by superimposing the individual electronic states of an ion and a solid. When the ion starts to move, the real-time propagation of all electron wave functions is treated. Also presented is a technique for gradually accelerating an ion up to a targeted velocity in order to minimize electronic excitations in the ion even without interaction with a solid surface. These techniques are suitable for analyzing bombardment of solids by highly charged, high-speed ions.

Effects of adrenalectomy (ADX) on analgesic potency and morphine (MOR) content after SC administration of 3.5 or 7 mg/kg of MOR, and effects of prednisolone (PRED) on the ADX-induced effects were studied. ADX significantly potentiated MOR analgesia at both MOR doses, and PRED reversed the ADX-induced potentiation of MOR analgesia. ADX did not affect MOR content in brain and plasma after 3.5 mg/kg MOR, but significantly increased MOR content in brain and plasma after 7 mg/kg MOR, and PRED reversed the ADX-induced increase in the MOR content. Although the analgesic potency of 3.5 mg/kg MOR in ADX group was equipotent with those of 7 mg/kg MOR in sham-operated and PRED-treated ADX groups, MOR content in the former group was significantly lower than those in the latter two groups. These results suggest that ADX potentiates MOR analgesia through both mechanisms of the increased MOR content and the increased sensitivity to MOR, and that the lack of glucocorticoids participates in both of these ADX-induced effects.

We have explored atomic and electronic structures of the interface consisting of crystalline Si and \ensuremath{\beta}-cristobalite ${\mathrm{SiO}}_{2}$ by performing first-principles total-energy electronic-structure calculations within the local-density-functional formalism. A stable atomic geometry has been attained by relaxing the atoms near the interface, according to the calculated forces on the atoms, toward the total-energy-optimized configuration. It is found that the epitaxial bond configuration of the \ensuremath{\beta}-cristobalite on Si(100) is stable after relaxation of the atoms on the first and second layers from the interface. In particular, the angle of the Si-O-Si bond near the interface is found to change upon relaxation from 180\ifmmode^\circ\else\textdegree\fi{}, the value in \ensuremath{\beta}-cristobalite, to 144\ifmmode^\circ\else\textdegree\fi{}, commonly observed in \ensuremath{\alpha}-quartz. In the resulting stable atomic geometry, there occur interface states in the Si energy-band gap, originating from the dangling-bond states of the twofold-coordinated interface Si atoms. Contrary to a prevailing picture that an electron is accommodated in each dangling bond, however, the calculated interface states split into two inequivalent states and thus one of the two is unoccupied and the other is occupied with electrons. This semiconducting character is shown to be a consequence of the electrostatic field caused by electron transfer from Si to oxygen through the interface.

Etude des mecanismes d'adsorption de l'oxygene sur des surfaces reconstruites par des calculs de structure bande et de force. Les atomes Si de surface et l'oxygene sont entierement relaxes, selon les forces calculees agissant sur les atomes, vers les configurations optimisees par l'energie totale. On trouve trois sites d'absorption (meta) stables pour l'atome d'oxygene. Le dimere original est preserve, macle ou decompose selon le site d'adsorption. La molecule O 2 se dissocie sur le dimere Si par transfert d'electron de la liaison disponible de Si a l'orbitale antiliante de O 2

We present a detailed picture of oxygen dissociation and adsorption on Si (100) surfaces on the basis of the first-principles total-energy force calculation within the local density functional formalism. We find several (meta)stable configurations for an adsorbed oxygen atom which is produced from exothermic dissociation of an oxygen dimer on the surface. Upon oxygen adsorption, the dimers formed on the Si clean surface are preserved, twisted or decomposed , depending on the site at which the oxygen is adsorbed. Experimental data available are found to be consistent with the present results.

In this article, we introduce a new approach based on the time-dependent density functional theory (TDDFT), where the real-time propagation of the Kohn-Sham wave functions of electrons are treated by integrating the time-evolution operator. We have combined this technique with conventional classical molecular dynamics simulation for ions in order to see very fast phenomena in condensed matters like as photo-induced chemical reactions and hot-carrier dynamics. We briefly introduce this technique and demonstrate some examples of ultra-fast phenomena in carbon nanotubes.

By combining ab initio time-dependent density functional calculations for electrons with molecular dynamics simulations for ions in real time, we investigate the microscopic mechanism of collisions between energetic protons and graphitic carbon nanostructures. We identify not only the amount of energy lost by the projectile, but also the electronic and ionic degrees of freedom of the target that accommodate this energy as a function of the impact parameter and projectile energy. Our results establish validity limits for the Born-Oppenheimer approximation and the threshold energy for defect formation in carbon nanostructures.

Using first-principles total-energy calculations, we investigated the atomic structure of a very thin Ti film on Si(001) and their intermixing. Our calculations show that the Ti film forms a pseudomorphic body-centered-tetragonal structure on Si(001). We found that intermixing of Ti and Si atoms energetically favors the formation of a C49-TiSi2 phase. We propose a plausible explanation of how the C49-TiSi2 phase and the interfacial structure between C49 phase and Si(001) are formed. We discuss why the transformation of the C49 phase into the C54 phase is inhibited when the TiSi2 dimensions reach the submicron region.

We present an improved ab initio time-dependent density-functional theory (TDDFT) approach to electronic excitations. A conventional TDDFT scheme within the local-density approximation (LDA) inaccurately predicts Rydberg and charge-transfer excitation energies, mainly because the electron-hole $(e\text{\ensuremath{-}}h)$ interaction is inappropriately described in these excitations, as can be found by analyzing the linear response formula [M. Petersilka, U. J. Gossmann, and E. K. U. Gross, Phys. Rev. Lett. 76, 1212 (1996)]. When the formula is averaged over the electron occupation, the inappropriate $e\text{\ensuremath{-}}h$ interaction within LDA is corrected to become explicitly similar to that of the exact exchange system. As anticipated from the similarity, our proposed scheme of modified linear response greatly improves the prediction of the problematic excitations, which are exemplified for typical molecules.

Mechanism of the ring-opening transformation in the photoexcited crystalline benzene is investigated on the femtosecond scale by a computational method based on the real-time propagation (RTP) time-dependent density functional theory (TDDFT). The excited-state dynamics of the benzene molecule is also examined not only for the distinction between the intrinsic properties of molecule and the intermolecular interaction but for the first validation using the vibration frequencies for the RTP-TDDFT approach. It is found that the vibration frequencies of the excited and ground states in the molecule are well reproduced. This demonstrates that the present method of time evolution using the Suzuki-Trotter-type split operator technique starting with the Franck-Condon state approximated by the occupation change of the Kohn-Sham orbitals is adequately accurate. For the crystalline benzene, we carried out the RTP-TDDFT simulations for two typical pressures. At both pressures, large swing of the C-H bonds and subsequent twist of the carbon ring occurs, leading to tetrahedral (sp3-like) C-H bonding. The nu4 and nu16 out-of-plane vibration modes of the benzene molecule are found mostly responsible for these motions, which is different from the mechanism proposed for the thermal ring-opening transformation occurring at higher pressure. Comparing the results between different pressures, we conclude that a certain increase of the intermolecular interaction is necessary to make seeds of the ring opening (e.g., radical site formation and breaking of the molecular character) even with the photoexcitation, while the hydrogen migration to fix them requires more free volume, which is consistent with the experimental observation that the transformation substantially proceeds on the decompression.

Combining time-dependent density functional calculations for electrons with molecular dynamics simulations for ions, we investigate the dynamics of excited carriers in a (3,3) carbon nanotube at different temperatures. Following an hν=6.8 eV photoexcitation, the carrier decay is initially dominated by efficient coupling to electronic degrees of freedom. At room temperature, the excitation gap is reduced to nearly half its initial value after ∼230 fs, where coupling to ionic motion starts dominating the decay. We show that the onset point and damping rate in the phonon regime change with initial ion velocities, a manifestation of temperature-dependent coupling between electronic and ionic degrees of freedom., A. R. was supported by the EC projects NANOQUANTA (No. NMP4-CT-2004-500198), SANES (No. NMP4-CT-2006-017310), Spanish MCyT, and the Humboldt Foundation. D. T. was supported by NSF NIRT Grants No. DMR-0103587, No. ECS-0506309, NSF NSEC Grant No. EEC-425826, and the Humboldt Foundation.

Graphite is the most stable form of carbon under room temperature and atmospheric pressure, and consists of two-dimensional honeycomb lattices with intralayer $s{p}^{2}$ bonding and rather weak van der Waals like interlayer interaction. When we supply gaseous small carbonic molecules such as methane to a patch of graphene, the patch will grow into graphite. Now, let us imagine a slightly different situation. Is a layered structure of graphite always formed, when we supply not methane molecules but another graphene patch? The answer from our computer simulations is ``No.'' Some graphene patches collide in parallel, but others at right angles, which result in a formation of junction structures (graphitic Y junctions). These junction structures are different from those of common sense for graphitic materials. Performing density functional calculations, we found that the reaction barrier height required for the formation of graphitic Y junctions are almost zero, and the binding energies per bond for each structure are $\ensuremath{\sim}1\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. Furthermore, tight-binding molecular dynamics simulations showed high thermal stability and high formation probabilities for these junction structures. As applications of graphitic Y junctions, we will present two interesting structures, where we focus on the magnetic properties of junction structures and nanotube T-junction structures which are different from conventional models. We expect that graphitic Y junctions might be hidden in graphitic soot and not characterized yet in experiment. 3D architectures constructed from those unit structures are expected to have various applications with lightweight, ferromagnet, high molecular storage and high thermal conductor.

We propose to use photodesorption as a noninvasive tool to clean carbon nanotubes from oxygen, offering a clear advantage over thermal and chemical treatments. The detachment of chemisorbed oxygen from atomic vacancies is triggered by a resonant Auger process, initiated by an O1s→O2p transition, which leaves two holes in the O2s level. In the electronically excited state, oxygen desorbs spontaneously, with no damage to the carbon network or the cylindrical nanotube shape. Subsequent reaction of oxygen atoms with H2 molecules is shown to prevent reoxidation of the nanotube., A.R. acknowledges support from the European Community 6th framework Network of Excellence NANOQUANTA (NMP4-CT-2004-500198) Spanish MCyT and the University of the Basque Country. D.T. was partly supported by the NSF-NIRT Grant No. DMR-0103587.

By carrying out ab initio total-energy calculations on incorporation of ${\mathrm{O}}_{2}$ into $\mathrm{Si}(001)$, we have reinvestigated possible initial oxidation structures and processes at the $\mathrm{Si}(001)$ surfaces. We found a new oxidation structure that is more stable than previously proposed backbond-oxidation models. The new structure is achieved by the oxidation process of ejecting $\mathrm{Si}$ atoms onto surfaces as observed in experiments. The atomic structure after the $\mathrm{Si}$ ejection is characterized by the ${\mathrm{O}}_{2}$-incorporated single dimer-vacancy $(\mathrm{O}2∕1\text{\ensuremath{-}}\mathrm{DV})$ structure. In particular, our finding indicates that the $\mathrm{Si}$ ejection also occurs at surfaces during initial stages of oxidation, in contrast to hitherto proposed $\mathrm{Si}$ ejection at ${\mathrm{SiO}}_{2}∕\mathrm{Si}$ interfaces.

We combined resonant photoabsorption and vibration spectroscopy with scanning tunneling microscopy (STM) to unambiguously identify the presence of Stone-Wales (SW) defects in carbon and boron nitride nanotubes. Based on extensive time-dependent ab initio density functional calculations, we propose to resonantly photoexcite SW defects in the infrared and ultraviolet regime as a means of their identification. Onset of nonradiative decay to a local defect vibration with a frequency of 1962 cm-1 serves as a fingerprint of such defects in carbon nanotubes. The bias dependence of the STM images shows distinct features associated with the presence of SW defects., Y.M. was supported by NAREGI Nanoscience Project, Ministry of Education, Culture, Sports, Science and Technology, Japan. A.R. acknowledges support from the EC grants (HPRN-CT-2000-00128 and HPRN-CT-2000-00167) and Spain MCyT. M.Y. and D.T. acknowledge partial support by NSF-NIRT grant DMR- 0103587.

We extend the time-dependent density functional formalism to study the microscopic response of defective nanotubes to electronic excitations. We find the lifetime of electronic excitations in these nanostructures to be several orders of magnitude longer than in solids, necessitating the use of excited-state molecular dynamics to correctly describe the atomic motion. We find that electronically excited nanotubes with monatomic vacancies show an unexpected self-healing ability, which is intimately linked to their nanometer size. © 2004 Elsevier B.V. All rights reserved., This work was performed under the management of the Frontier Carbon Technology supported by NEDO. D.T. and M.Y. acknowledge partial support by NSF-NIRT grant DMR-0103587. A.R. was supported by the European Community research and training network COMELCAN (HPRN-CT-2000- 00128), MCyT of Spain Grant MAT2001-09, and Basque Country University.

One of challenging application of carbon nanotubes is nano-scaled electronic device, in which precise control of defects and carriers is required in analogy of silicon-based technology. In this work, we show that optical excitations can be promising tools to analyze and control defects in nanotubes being alternative to conventional heattreatments. We performed ab initio calculations, which solve the time-dependent Schrodinger equations for electrons on real-time axis as well as classical Newton’s equations of motions for ions. This method is also useful to investigate carrier dynamics under finite temperatures. These works were done under collaboration with Prof. Angel Rubio, Prof. David Tomanek, Dr. Savas Berber, and Miss Mina Yoon.

We performed tight-binding molecular-dynamics simulations of the reactive collision of graphitic patches and found that nuclei of nanotube, nanohorn, and nanocage were formed after the collision. In the reaction, chemicalbonds were initially formed at one to three edges depending on the relative stacking of the patches, which was followed by the capping process that depends sensitively on the temperatures. These results indicate that the patches in the gas phase are a good precursor of carbon nano-objects and suggest the possibility of controlling the nucleation process with temperature or pressure.

Three ${\mathrm{C}}_{20}$ isomers ring, bowl, and cage were studied according to hybrid density-functional theory. We determined the stable geometries of neutral and negatively charged clusters, and then calculated their infrared light, Raman, and anion photoelectron spectra. The neutral cage clusters of ${\mathrm{C}}_{i}$ and ${\mathrm{C}}_{2h}$ symmetries are found to have close energies and the calculated photoelectron spectra corresponding to both symmetries resemble experimental spectrum; thus, we give clear assignment of the observed spectrum. On the contrary, we found that there is some difference between the calculated and measured spectra of the bowl, implying that the electron correlation effect plays an important role in this isomer. The measured electron affinities are well reproduced by theoretical calculations. Moreover, a calculation on the vibronic coupling suggests that the solids synthesized from cage ${\mathrm{C}}_{20}$ are candidates for superconductors. To evaluate the stability of the isomers, we estimated the free energy by taking into account the vibrational effect.

By carrying out first-principles calculations on diamond-forming processes, we predict a method for the heteroepitaxial growth of diamond on cubic beta-SiC(001). In the method, we used two processes: (i) the preformation of an sp(3)-like surface configuration of beta-SiC(001) by the adsorption of group-V surfactants; (ii) the successive growth of diamond by the segregation of the surfactants onto a surface and the desorption of surface hydrogen. Analyzing the segregation energies, we found that the atomic size effect plays a crucial role in the surfactant-mediated growth of diamond on beta-SiC(001).

Presentado al "Tsukuba Symposium on Carbon Nanotube" in commemoration of the 10th Anniversary of its discovery., Stability test of nanotubes with presence of single vacancies has been performed by means of tight-binding molecular dynamics and electron–ion dynamics within the framework of the density functional theory. A4Â diameter nanotube having a single vacancy with three dangling bonds has been found to retain its cylindrical shape under high temperature around 4000K, despite its large internal strain energy. Meanwhile, an electronic excitation of vacancy-related state has shown considerable atomic displacement, which may cause extraordinary large lattice vibration or nanotube decay. Furthermore, the single vacancy can stabilize itself by making carbon dimer to remain with only one dangling bond. Narrower nanotubes tend to prefer this self-stabilization and thus could be tolerant to the presence of defects

We demonstrate through extensive first-principles time-dependent density functional calculations that attractive van der Waals interaction between closed-shell atoms can be enhanced by light with constant spatial intensity. We illustrate this general phenomenon for a He dimer as a prototypical case of complex van der Waals interactions and show that when excited by light with a frequency close to the 1s → 2p He-atomic transition, an attractive force larger than 7 pN is produced. This force gain is manifested as a larger acceleration of He-He contraction under an optical field. The concerted dynamical motions of the He atoms together with polarity switching of the charge-induced dipole cause the contraction of the dimer. These findings are relevant for the photo-induced control of weakly bonded molecular species, either in gas phase or in solution., A.R. acknowledges financial support from the European Research Council Advanced Grant DYNamo (ERC-2010-AdG-267374), Spanish Grant (FIS2010-21282-C02-01), Grupos Consolidados del Gobierno Vasco (IT578-13), and European Commission project CRONOS (Grant No. 280879-2). H.Z. acknowledges financial support from the National Natural Science Foundation of China (NSFC Grant No. 11074176 and NSAF Grant No. 10976019) and support from the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100181110080).

Using density functional theory, we calculate the charge redistribution incurred upon forming multiwall carbon nanotubes, or by sandwiching initially isolated single-wall nanotubes between graphene layers. In these systems, we observe a significant charge transfer between the \ensuremath{\pi} electron system of the tube walls and a newly formed interlayer state. We discuss the direction of charge flow in terms of the interlayer hybridization and work function differences in the composite systems.

We investigated the coalescence of ultrathin carbon nanotubes (UTCNTs) using the tight-binding molecular dynamics simulation technique. We have found that two UTCNTs having the same or different chirality can coalesce without initially introducing atomic defects to enhance the reaction. The chiral index of the coalesced nanotube was found to be given as a vector sum of the indices of the original nanotubes, which can be explained geometrically in terms of the developments of the nanotubes. The results clearly show that the chirality can be changed through chemical reaction, which might suggest a possibility of chirality control.

We report on a first-principles total-energy calculation that provides the energetics and electronic structure of stable polymerized fullerites consisting of the smallest fullerene ${\mathrm{C}}_{20}.$ We find that the ${\mathrm{C}}_{20}$ fullerene has periodic three-dimensional covalent networks with orthorhombic and tetragonal symmetries. Both are found to be energetically stable and to be elemental semiconductors with a moderate energy gap of about 1.5 eV. Substantially high peaks of the density of states are found to appear below the top of the valence band, suggesting that these materials under hole-doped conditions are candidates for superconductors.

${\mathrm{C}}_{20}$ cages consisting only of pentagons have been synthesized in a gas phase. [H. Prinzbach et al., Nature (London), 407, 60 (2000)]. By performing first-principles calculations, we have found that the ${\mathrm{C}}_{20}$ cages can form condensed phases in several dimensions. The most stable phase among the investigated ones is a simple-cubic-like (SCL) phase, which shows a metallic property. Meanwhile, a metastable one-dimensional phase (1D chain) is found to be a semiconductor. The computed band structure of a 1D chain shows high density of states near the Fermi level compared to the SCL phase, which is a promising sign of superconductivity under carrier doping.

We study the electronic structure and energetics of the nanotubes, (8,8), (9,9), and (10,10), encapsulating a linear chain of C60 by using the local density approximation in the density functional theory. We find that the encapsulating process is exothermic for the (10,10) nanotube, whereas the processes are endothermic for the (8,8) and (9,9) nanotubes. We also find that the stable C60@(10,10) is a metal with multi-carriers each of which distributes either along the nanotube or on the C60 chain. This unusual feature is due to the nearly free electron state that is inherent to hierarchy solids with sufficient space inside.

By using first-principles calculations, we calculate the vibronic fine structure in photoelectron spectra of C-20 clusters. Based on our results, we assign one of the recently observed spectra [H. Prinzbach et al., Nature (London) 407, 60 (2000)] to the fullerene structure and, therefore, confirm the experimental claim that the smallest fullerene is really synthesized.