Momentum space properties for the atoms helium to neon from energy‐optimized explicitly correlated wave functions

Abstract

AbstractAtomic momentum space properties have been calculated starting from explicitly correlated wave functions. The one‐body momentum distribution and some of their radial moments and related properties for the atoms helium to neon are reported. The wave functions include a generalized Jastrow factor and in some cases a multideterminant expansion to take care of the nondynamic correlation effects such as the 2s‐2p near degeneracy. Both the variational trial wave functions and the momentum space properties have been calculated using the variational Monte Carlo method. The optimization of the free parameters of the trial wave functions is done by using a recently developed energy‐optimization technique. Most of the previous variational Monte Carlo applications to quantum chemistry rely on variance‐optimized wave functions. A comparison of momentum space properties calculated with energy‐optimized wave functions with those obtained by means of variance‐optimized wave functions shows a better performance of the former. Despite the simple parameterization of the wave functions used here, they present a good agreement with the results obtained from extensive configuration interaction wave functions. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004