Dispersion interactions in dimers of inert gases: Investigation by means of explicitly correlated coupled clusters CCSD(F12)(T)

Abstract

Dispersion interactions in He2, Ne2, and Ar2 dimers are investigated using the explicitly correlated method CCSD(F12)(T) with numerical quadratures. The obtained energies of interaction agree well with the results from highly accurate CCSD(T) calculations described in works in which sets of bonded functions are used. It is shown that in order to attain high accuracy in estimating energies of interaction, the exponential parameter of Slater-type geminals in the CCSD(F12)(T) method must be optimized. The higher accuracy of the values of C 6 asymptotic coefficients found using the CCSD(F12)(T) method instead of the conventional CCSD(T) approach is established, demonstrating the importance of considering short-range electron correlation effects in asymptotic regions of potential surfaces where the interaction between atoms is of a long-range dispersion nature.