XVIth International Workshop on Quantum Systems in Chemistry and Physics 

Abstract 
Timedependent multiconfiguration wave function theory for molecular systems composed of two kinds of Fermi particles: Application to diatomiclike molecules 
Tsuyoshi Kato and Kaoru Yamanouchi
Department of Chemistry, School of Science, The University of Tokyo, Japan 
We propose multiconfiguration wave function theory for molecular systems composed of two kinds of Fermi particles, e.g., electrons and protons, and two heavy nuclei to describe molecular dynamics in intense laser fields. For practical applications of the theory we reduce the dimension of the consitituent orbital functions from 3D to 2D. To that end we make use of "diatomiclike molecular picture" for molecules such as CH_{3}OH, C_{2}H_{2}, and CH_{2}CH_{2}.
First, we calculate the electroprotonic ground state wave function of CH_{3}OH within the fixed nuclear model in which C and O atoms are fixed in space. By analyzing the conditional probability density functions for the protonic system, which are calculated by using the 2nd order reduced density matrix for the protonic structure, we examine the positional correlations of four protons. We find that the positional correlations are close to those in the optimized geometrical structure obtained by the standard BornOppenheimer approach, which assures applicability of our present nonBorn Oppenheimer approach.
Another example includes the calculation of the CIvectors that are newly introduced in our theory to elucidate the physical meaning of the CIvectors. From the analysis of the electrovibrational ground state wave function of 1D hydrogen molecule, we find that the effects of nonadiabatic couplings between adiabatic electronic states in the BornOppenheimer picture are properly described in the present method as the variations of the CIvectors.


