The higher-order C_n dispersion coefficients for hydrogen
arXiv:physics/0411172 · doi:10.1103/PhysRevA.71.032709
Abstract
The complete set of 2nd, 3rd and 4th order van der Waals coefficients, C_n up to n=32 for the H(1s)-H(1s) dimer are computed using pseudo-states to evaluate the appropriate sum rules. A study of the convergence pattern for n<=16 indicates that all the C_n (n<=16) coefficients are accurate to 13 significant digits. The relative size of the 4th-order C^4_n to the 2nd-order C^2_n coefficients is seen to increase as n increases and at n=32 the 4th-order term is actually larger.
5 pages under review PRA