Accurate Dissociation Energies of He_2 and Be_2 Calculated by MRCI Method

摘要

The dissociation energies of He_2 and Be_2 have been calculated by extrapolating to the infinite basis of the BSSE corrected MRCI total energies obtained with large finite Gaussian basis sets and pseudo-natural molecular orbitals. The calculated He_2 dissociation energy of 11.0012 K is in excellent agreement with the value of 10.998 ± 0.005 obtained recently by the quantum Monte Carlo method. The dissociation energy of 796 cm~(-1) of Be_2 is in a good agreement with the experimental value of 790 ± 30 cm~(-1).