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The collision reaction H + Cl+ assisted by the ultra-short laser pulse is investigated using the time-dependent quantum wave packet method. The probability of dissociation depends on the yield ratio of association product HCl+. The greater the laser frequency is, the lower the vibrational level of HCl+ is. With lowering laser frequency, the probabilities of photoassociation and photodissociation increase, and the ratio of products H+ + Cl(2P0) to H(2S) + Cl+(1D) also increases. The kinetic energy spectra of the dissociated fragments at low frequency are wider than those at high frequency. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [ABSTRACT FROM AUTHOR]

A detailed investigation has been performed at the QCISD(T)/6‐311++G(d,p)//B3LYP/6‐311+G(d,p) level for the reaction of NCO with C2H5 by constructing singlet and triplet potential energy surfaces (PES). The results show that the title reaction is more favorable on the singlet PES than on the triplet PES. On the singlet PES, the initial addition processes are barrierless and release lots of energy. The dominant channel occurs via the fragmentations of the initial adduct C2H5NCO and C2H5OCN to form C2H4 + HNCO and HOCN, respectively. With higher barrier heights, other products such as CH4 + HNC + CO, CH3CHNH + CO, CH3CH + HNCO, and CH3CN + H2 + CO are less competitive. On the triplet PES, the entrance reactions surpass significant barriers; therefore, it could be negligible at the normal atmospheric condition. However, the most feasible channel on the triplet PES is the direct hydrogen abstraction channel to form CH2CH2 + HNCO. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

A direct ab initio dynamics method is used to investigate the hydrogen-abstraction reaction of H2CO with NCO. The potential energy surface information is obtained at the MP2/6-311G(d,p) level. More accurate single-point energy is refined at the G3(MP2)//MP2/6-311G(d,p) level. Furthermore, the rate constants of reaction H2CO + NCO are evaluated by using the canonical variational transition state theory with small-curvature tunneling contributions over a wide temperature range of 200–2000 K. The calculated reaction enthalpy and rate constants are in good agreement with the available experimental values. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 394–400, 2009 [ABSTRACT FROM AUTHOR]

ABSTRACT: Stability and electronic property calculations are performed systematically based on density functional theory at the B3LYP/6-31G(d) level for Td C28 fullerene and exohedral fluorine and trifluoromethyl derivatives C28F4–n(CF3)n (n = 0,1,2,3,4). All the exohedral derivatives that are on the potential energy surfaces are kinetically stable with large HOMO-LUMO gaps. Further investigations show that binding energies of C28F4–n(CF3)n (n = 0,1,2,3,4) molecules are positive, suggesting they are thermodynamically stable. An analysis of the π-orbital axis vector indicates the high strain in Td C28 cage could be greatly released by fluorine and trifluoromethyl decorations. Mulliken charge analysis reveals that adding different electron groups to the Td C28 cage can cause remarkably different charge populations. In addition, from the ionization potential and electron affinity investigations, the C28F4–n(CF3)n (n = 0,1,2,3,4) molecules manifest weak redox properties. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [ABSTRACT FROM AUTHOR]

The mechanisms for the reaction of C2H5S with NO2 are investigated at the QCISD(T)/6-311++G(d, p)//B3LYP/6-311++G(d, p) level on both single and triple potential energy surfaces. The geometries, vibrational frequencies and zero-point energy (ZPE) corrections of all stationary points involved in the title reaction are calculated at the B3LYP/6-311++G(d, p) level. The results show that the reaction is more predominant on the single potential energy surface, while it is negligible on the triple potential energy surface. Without barrier height in the whole process, the major channel is R → C2H5SONO (IM1 and IM2) → P1 (C2H5SO+NO). With much heat released in the formation of C2H5SNO2 (IM3) and the transition state involved in the subsequent step more stable than reactants, P4 (CH3CHS + t-HONO) is subdominant product energetically. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [ABSTRACT FROM AUTHOR]

The mechanisms for the reaction of CH3S with NO2 are investigated at the QCISD(T)/6-311++G(d,p)//B3LYP/6-311++G(d,p) on both single and triple potential energy surfaces (PESs). The geometries, vibrational frequencies, and zero-point energy (ZPE) correction of all stationary points involved in the title reaction are calculated at the B3LYP/6-311++G(d,p) level. More accurate energies are obtained at the QCISD(T)/6-311++G(d,p). The results show that 5 intermediates and 14 transition states are found. The reaction is more predominant on the single PES, while it is negligible on the triple PES. Without any barrier height for the whole process, the main channel of the reaction is to form CH3SONO and then dissociate to CH3SO+NO. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [ABSTRACT FROM AUTHOR]

The potential energy surface information of the CH2CO + CN reaction is obtained at the B3LYP/6-311+G(d,p) level. To gain further mechanistic knowledge, higher-level single-point calculations for the stationary points are performed at the QCISD(T)/6-311++G(d,p) level. The CH2CO + CN reaction proceeds through four possible mechanisms: direct hydrogen abstraction, olefinic carbon addition–elimination, carbonyl carbon addition–elimination, and side oxygen addition–elimination. Our calculations demonstrate that R→IM1→TS3→P3: CH2CN + CO is the energetically favorable channel; however, channel R→IM2→TS4→P4: CH2NC + CO is considerably competitive, especially as the temperature increases (R, IM, TS, and P represent reactant, intermediate, transition state, and product, respectively). The present study may be helpful in probing the mechanism of the CH2CO + CN reaction. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [ABSTRACT FROM AUTHOR]

A detailed theoretical survey of the potential energy surface (PES) for the CH2CO + O(3P) reaction is carried out at the QCISD(T)/6-311+G(3df,2p)//B3LYP/6-311+G(d,p) level. The geometries, vibrational frequencies, and energies of all stationary points involved in the reaction are calculated at the B3LYP/6-311+G(d,p) level. More accurate energy information is provided by single-point calculations at the QCISD(T)/6-311+G(3df,2p) level. Relationships of the reactants, transition states, intermediates, and products are confirmed by the intrinsic reaction coordinate (IRC) calculations. The results suggest that P1(CH2+CO2) is the most important product. This study presents highlights of the mechanism of the title reaction. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [ABSTRACT FROM AUTHOR]