TY - JOUR
T1 - Development of analytic energy gradient method in nuclear orbital plus molecular orbital theory
AU - Hoshino, Minoru
AU - Tsukamoto, Yasuhiro
AU - Nakai, Hiromi
PY - 2007/11/15
Y1 - 2007/11/15
N2 - This study formulates the analytic energy gradients in the Hartree-Fock calculations of the NOMO theory, which simultaneously determines nuclear and electronic wave functions without the Born-Oppenheimer approximation. The formulations correspond to the translation- and rotation-contaminated (TRC), translation-free (TF), and translation- and rotation-free (TRF) treatments. The optimizations of the orbital centers for several diatomic molecules, which have been performed by using the analytic energy gradients, have given the averaged nuclear distances [R0] reflecting the quantum effects of nuclei and the anharmonicity of the potential energy surfaces. The numerical assessments have clarified that the effects of eliminating the translational and rotational contaminations, i.e., the TRF effects are important to improve the evaluations of {R0}, especially for the molecules including hydrogen atoms.
AB - This study formulates the analytic energy gradients in the Hartree-Fock calculations of the NOMO theory, which simultaneously determines nuclear and electronic wave functions without the Born-Oppenheimer approximation. The formulations correspond to the translation- and rotation-contaminated (TRC), translation-free (TF), and translation- and rotation-free (TRF) treatments. The optimizations of the orbital centers for several diatomic molecules, which have been performed by using the analytic energy gradients, have given the averaged nuclear distances [R0] reflecting the quantum effects of nuclei and the anharmonicity of the potential energy surfaces. The numerical assessments have clarified that the effects of eliminating the translational and rotational contaminations, i.e., the TRF effects are important to improve the evaluations of {R0}, especially for the molecules including hydrogen atoms.
KW - Energy gradient
KW - Non-Born-Oppenheimer theory
KW - Nuclear orbital plus molecular orbital theory
KW - Optimization
KW - Vibrational averaging
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U2 - 10.1002/qua.21430
DO - 10.1002/qua.21430
M3 - Article
AN - SCOPUS:35248862108
VL - 107
SP - 2575
EP - 2585
JO - International Journal of Quantum Chemistry
JF - International Journal of Quantum Chemistry
SN - 0020-7608
IS - 14
ER -