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Potential energy surface

About: Potential energy surface is a research topic. Over the lifetime, 11674 publications have been published within this topic receiving 307691 citations.


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TL;DR: In this paper, the rotational (de)excitation of CO by ground state para- and ortho-H_2 is obtained using quantum scattering calculations for collision energies between 1 and 520 cm^{-1}.
Abstract: Cross sections for the rotational (de)excitation of CO by ground state para- and ortho-H_2 are obtained using quantum scattering calculations for collision energies between 1 and 520 cm^{-1}. A new CO-H_2 potential energy surface is employed and its quality is assessed by comparison with explicitly correlated CCSD(T)-R12 calculations. Rate constants for rotational levels of CO up to 5 and temperatures in the range 5-70 K are deduced. The new potential is found to have a strong influence on the resonance structure of the cross sections at very low collision energies. As a result, the present rates at 10 K differ by up to 50% with those obtained by \citet{flower01} on a previous, less accurate, potential energy surface.

106 citations

Journal ArticleDOI
TL;DR: The theoretically predicted branching between molecules and radicals in the thermal decomposition of acetaldehyde is in reasonable agreement with the corresponding shock tube measurement described in the companion paper.
Abstract: A novel theoretical framework for predicting the branching between roaming and bond fission channels in molecular dissociations is described and applied to the decomposition of acetaldehyde. This reduced dimensional trajectory (RDT) approach, which is motivated by the long-range nature of the roaming, bond fission, and abstraction dynamical bottlenecks, involves the propagation of rigid-body trajectories on an analytic potential energy surface. The analytic potential is obtained from fits to large-scale multireference ab initio electronic structure calculations. The final potential includes one-dimensional corrections from higher-level electronic structure calculations and for the effect of conserved mode variations along both the addition and abstraction paths. The corrections along the abstraction path play a significant role in the predicted branching. Master equation simulations are used to transform the microcanonical branching ratios obtained from the RDT simulations to the temperature- and pressure-dependent branching ratios observed in thermal decomposition experiments. For completeness, a transition-state theory treatment of the contributions of the tight transition states for the molecular channels is included in the theoretical analyses. The theoretically predicted branching between molecules and radicals in the thermal decomposition of acetaldehyde is in reasonable agreement with the corresponding shock tube measurement described in the companion paper. The prediction for the ratio of the tight to roaming contributions to the molecular channel also agrees well with results extracted from recent experimental and experimental/theoretical photodissociation studies.

106 citations

Journal ArticleDOI
Chuanxiu Xu1, Daiqian Xie, Dong H. Zhang, Shi Ying Lin, Hua Guo 
TL;DR: A new global potential-energy surface for the ground electronic state of HO(2)(X(2)A(")) has been developed by three-dimensional cubic spline interpolation of more than 15 000 ab initio points, which were calculated at the multireference configuration-interaction level with Davidson correction using the augmented correlation-consistent polarized valence quadruple zeta basis set.
Abstract: A new global potential-energy surface for the ground electronic state of HO(2)(X(2)A(")) has been developed by three-dimensional cubic spline interpolation of more than 15 000 ab initio points, which were calculated at the multireference configuration-interaction level with Davidson correction using the augmented correlation-consistent polarized valence quadruple zeta basis set. Low-lying vibrational states were obtained in this new potential using the Lanczos method and assigned. The calculated vibrational frequencies are in much better agreement with the available experimental band origins than those obtained from a previous potential. In addition, rate constants for the H+O(2) O + OH reactions were obtained using a wave-packet-based statistical model. Reasonably good agreement with experimental data was obtained. These results demonstrate the accuracy of the potential.

105 citations

Journal ArticleDOI
TL;DR: In this article, the state-selected reaction rates were calculated by an extension of variational transiton state theory, where the reactant vibrational modes were assumed to correlate diabatically with generalized normal modes of a generalized activated complex.
Abstract: The state‐selected reaction rates OH(nOH = 0,1)+ H2(nHH = 0,1)→H2O+H are calculated by an extension of variational transiton state theory. The reactant vibrational modes are assumed to correlate diabatically with generalized normal modes of a generalized activated complex. Using the Walch‐Dunning‐Schatz‐Elgersma ab initio potential energy surface, the theory predicts that excitation of H2 is 19–68 times more effective than excitation of OH in promoting reaction at 300 K, where the range of values corresponds to different possible assumptions about the quantal effects on reaction‐coordinate motion. These values are in much better agreement with the experimental value (about 100) than is a calculation based on the conventional transition state, which yields 2×104.

105 citations

Journal ArticleDOI
TL;DR: Takada and Nakamura as discussed by the authors calculated tunneling energy splittings of vibrationally excited states using several models of two-dimensional symmetric double well potentials, depending on the topography of potential energy surface; the symmetry of the mode coupling plays an essential role.
Abstract: Tunneling energy splittings of vibrationally excited states are calculated quantum mechanically using several models of two‐dimensional symmetric double well potentials. Various effects of vibrational excitation on tunneling are found to appear, depending on the topography of potential energy surface; the symmetry of the mode coupling plays an essential role. Especially, oscillation of tunneling splitting with respect to vibrational quantum number can occur and is interpreted by a clear physical picture based on the semiclassical theory formulated recently [Takada and Nakamura, J. Chem. Phys. 100, 98 (1994)]. The mixed tunneling in the C region found there allows the wave functions to have nodal lines in classically inaccessible region and can cause the suppression of the tunneling. The above analysis is followed by the interpretation of recent experiments of proton tunneling in tropolone. Ab initio molecular orbital calculations are carried out for the electronically ground state. A simple three‐dimensio...

105 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023128
2022206
2021288
2020322
2019295
2018310