原子核と電子の波動関数を同時に決定するためのnon-Born-Oppenheimer 理論：NOMO 理論

抄録

We review a recent development in a rigorous non-Born-Oppenheimer method, i.e., nuclear orbital plus molecular orbital (NOMO) method, which determines the nuclear and electronic wave functions simultaneously. The NOMO theory is an exact theory for the non-BO problem in principle; for example, full-configuration interaction formulation for a complete configuration space. Hartree-Fock equations for nuclear orbitals and molecular orbitals are derived for practical calculations. The usage of Gaussian basis functions for nuclear orbitals is discussed. We formulate the elimination of translational and rotational contaminations in the NOMO method. Furthermore, many-body effects such as nucleus-nucleus, nucleus-electron, and electron-electron correlations are investigated by applying the second-order Møller-Plesset perturbation theory to the NOMO method. The excited-state theories such as configuration interaction and generator coordinate method are examined to describe not only electronic but also vibrational excited states.