Vibrational quasi-degenerate perturbation theory: applications to fermi resonance in CO2, H2CO, and C6H6

• Published in: Physical chemistry chemical physics : PCCP Vol. 10; no. 13; pp. 1781 - 1788
• Main Authors: Yagi, Kiyoshi, Hirata, So, Hirao, Kimihiko
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2008
• Subjects: Absorption; Benzene - analysis; Carbon Dioxide - analysis; Chemistry; Chemistry, Physical - methods; Computer Simulation; Exact sciences and technology; Formaldehyde - analysis; General and physical chemistry; Models, Statistical; Molecular Structure; Spectrophotometry - methods; Perturbation theory; Vibrational interaction; Correlation; Mode coupling; Reference; Wave function; Infrared absorption; Theoretical study; Configuration interaction; Algorithm; Perturbation method; Dynamics; Frequency; Resonance; SCF calculations

A quasi-degenerate perturbation method with vibrational self-consistent field (VSCF) reference wavefunction is developed. It simultaneously accounts for strong anharmonic mode-mode coupling among a few states (static correlation) by a configuration interaction theory and for weak coupling with a vas...