Variationally determined multipole Cauchy moments

Abstract

The hydrodynamic variational method for obtaining dynamic multipole polarizabilities is extended to determine multipole Cauchy moments. The hydrodynamic functional is replaced by an equivalent series of functionals, obtained by expanding the first-order functions in power series of the applied frequency. As an application of the method, multipole Cauchy moments for the ground states of atomic hydrogen and helium are determined by solving variationally the set of functionals. The resulting moments are then used to construct Padé approximants, from which long-range dispersion coefficients are determined.

Dispersion coefficients for interactions between hydrogen and helium atoms with Coulomb and screened Coulomb potentials

“…We have obtained results for the dispersion C 8 , C 10 , C 12 coefficients for the interactions between the hydrogen and helium atoms in their ground states using a highly correlated exponential basis set for He and a Slater-type basis set for H. The Van der Walls force constants, particularly the leading term C 6 arising from the induced dipoles, are of great theoretical and experimental interest in atomic, molecular physics [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

“…Utilizing established and powerful computational aspects [1][2][3][4][5][6][7][8], in this work, we have investigated the effect of screened Coulomb potentials on the dispersion coefficients for interaction between hydrogen and helium atoms. Besides several theoretical investigations on the dispersion coefficients for the interactions among H and He [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], the studies have also been presented to investigate the C 6 , C 8 and C 10 coefficients for the He-He system [7,8] and the H-H system [7,20], and the C 6 coefficient for the H-He interaction [7] in the screening environments. The purpose of this paper is to present new results of dispersion coefficients C 8 , C 10 , C 12 for the H-He system as functions of the screening parameters ranging from 0 to 1a −1 0 .…”