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DFT simulations may be inaccurate in modeling aqueous systems, with results depending on the choice of the exchange-correlation functional. Here, the authors present an integrative method called HF-r2SCAN-DC4 that provides near chemical accuracy in electronic structure information not only for pure water but also for molecules dissolved in it

Nanosized drug delivery systems typically enter the cell via endocytosis. However, a significant amount of the endocytosed cargo cannot effectively escape from the endosome, resulting in drug degradation. Therefore, there are several ongoing efforts to develop transmembrane delivery systems that could circumvent endocytosis. In this study, phospholipid nanotube nanodrills (LDs) were formed onto the surface of a human serum albumin nanoparticle via self-assembling phospholipids. The nanodrill technology enhanced the intracellular uptake efficiency of nanoparticles via energy-independent direct cell membrane permeation. The length of the nanodrills according to the DSPE-PEG to DSPC ratio was investigated both experimentally and theoretically. Our findings demonstrated that longer nanodrills were formed on the surface of the nanoparticles as the ratio of DSPC (i.e., a strongly hydrophobic lipid) in the two phospholipids increases. Moreover, the intracellular uptake efficiency increased as the length of phospholipid nanodrills increased. In addition to enhancing intracellular delivery, the phospholipid nanodrills could penetrate the extracellular matrix and enable the introduction of nanoparticles, thus highlighting the promising tissue penetration capacity of phospholipid nanodrill technology. The improved cell permeability of LD technology was demonstrated by effectively inhibiting specific genes via siRNA-based therapeutic delivery. Moreover, this approach enhanced the efficacy of chemotherapeutics against chemo-resistant cancer cells. Therefore, LD technology could be used to deliver genetic materials and chemical-based therapeutics both in vitro and in vivo.

Time evolution of the charge-transfer site population is studied in a short DNA sequence to determine the type of governing charge-transfer mechanism. Partial density matrixes of the incoherent hopping and coherent superexchange pathways as well as full reduced density matrix are evaluated and discussed for both debye and ohmic baths.

Standard density functional approximations often give questionable results for odd-electron radical complexes, with the error typically attributed to self-interaction. In density corrected density functional theory (DC-DFT), certain classes of density functional theory calculations are significantly improved by using densities more accurate than the self-consistent densities. We discuss how to identify such cases, and how DC-DFT applies more generally. To illustrate, we calculate potential energy surfaces of HO· Cl− and HO·H2O complexes using various common approximate functionals, with and without this density correction. Commonly used approximations yield wrongly shaped surfaces and/or incorrect minima when calculated self consistently, while yielding almost identical shapes and minima when density corrected. This improvement is retained even in the presence of implicit solvent. [ABSTRACT FROM AUTHOR]

We introduce a simple semiempirical anharmonic Kirkwood–Keating potential to model AxB1-xC-type semiconductors. The potential consists of the Morse strain energy and Coulomb interaction terms. The optical constants of pure components, AB and BC, were employed to fit the potential parameters such as bond-stretching and -bending force constants, dimensionless anharmonicity parameter, and charges. We applied the potential to finite temperature molecular-dynamics simulations on AlxGa1-xAs for which there is no lattice mismatch. The results were compared with experimental data and those of harmonic Kirkwood–Keating model and of equation-of-motion molecular-dynamics technique. Since the Morse strain potential effectively describes finite temperature damping, we have been able to numerically reproduce experimentally obtained optical properties such as dielectric functions and reflectance. This potential model can be readily generalized for strained alloys. [ABSTRACT FROM AUTHOR]

The various mechanisms involved in the reversible transformation of the helical rods and straight tods into the different elliptical macrocycles assembly are discussed. The transformation is shown to be highly based on the molecular length of the elliptical macrocycle.

The formation of stepped strips from self-assembly of molecular rods with laterally attached flexible chains is described. The self-assembling rod molecules forming these aggregates have an oligo(p-phenylene) rod and penta(ethylene oxide) branched chains that are grafted together at the mid part of the rod.

The excitation energy transfer process of meso-meso linked zinc(II) porphyrin arrays are examined by using the on-the-fly filtered propagator path integral method. The studies have shown that the coherence length is the result of electronic and environmental effect rather than the structure disorder.

The distance dependent variation of the coherence length relevant to DNA charge-transfer processes within 5'-G[A.sub.n][G.sub.3]-3' DNA sequences is examined. The coherence within a collective state has governed the overall charge transfer, which is composed of a part of a sequence within the coherence length from the donor.

An accurate quantitative analysis on bridge-mediated pathways in long-range charge transfer process is described with the density matrix decomposition scheme of the path integral method. In the presence of the coherence, the long-range charge transfer dynamics are dominated by the through-bridge mechanism that consists of the coherent through-bridge pathways as well as the incoherent nearest-neighbor hopping pathways.

The characteristics of quantum dynamically important paths are examined by using the on-the-fly filtered propagator functional path integral method, which evaluates a numerically accurate reduced density matrix by ignoring the majority of paths with insignificant contribution to the dynamics of the rest. The results have shown that it is possible to evaluate the accurate dynamics of bridge-mediated long-range charge-transfer systems efficiently in a significantly reduced quantum mechanical trajectory space.

We review the role of self-consistency in density functional theory (DFT). We apply a recent analysis to both Kohn-Sham and orbital-free DFT, as well as to partition DFT, which generalizes all aspects of standard DFT. In each case, the analysis distinguishes between errors in approximate functionals versus errors in the self-consistent density. This yields insights into the origins of many errors in DFT calculations, especially those often attributed to self-interaction or derealization error. In many classes of problems, errors can be substantially reduced by using better densities. We review the history of these approaches, discuss many of their applications, and give simple pedagogical examples. [ABSTRACT FROM AUTHOR]

Cyclic conjugated molecules have relatively planar conformations due to overlap of adjacent p-orbitals of delocalized electrons and which is strongly correlated with the degree of electron delocalization. We first demonstrate the quantitative relationship between structural heterogeneity and two structural parameters: out-of-plane distances of atoms and torsional angles between neighbouring aromatic moieties. The molecular characteristic-dependent trend of planarity is presented in terms of these two parameters for the number of unit moieties, type and distribution of linkers, and substituting alkyl groups. The method presented may provide a simple yet systematic guide for determining the degree of delocalization of cyclic conjugated molecules. [ABSTRACT FROM AUTHOR]

We decompose the energy error of any variational density functional theory calculation into a contribution due to the approximate functional and that due to the approximate density. Typically, the functional error dominates, but in many interesting situations the density-driven error dominates. Examples range from calculations of electron affinities to preferred geometries of ions and radicals in solution. In these abnormal cases, the error in density functional theory can be greatly reduced by using a more accurate density. A small orbital gap often indicates a substantial density-driven error. [ABSTRACT FROM AUTHOR]