Visualizing Molecular Wavefunctions Using Monte Carlo Methods

Using explicitly correlated wavefunctions and variational Monte Carlo we calculate the electron density, the electron density difference, the intracule density, the extracule density, two forms of the kinetic energy I density, the Laplacian of the electron density, the Laplacian of the intracule density, and the Laplacian of the extracule density on a dense grid of points for the ground state of the hydrogen molecule at three internuclear distances (0.6, 1.4, 8.0). With these values we construct a contour plot of each function and describe how it can be used to Visualize the distribution of electrons in this molecule. We also examine the influence of electron correlation on each expectation value by calculating each function with a Hartree-Fock wavefunction and then comparing these values With Our explicitly correlated values. (C) 2008 Wiley Periodicals, Inc. Int J Quantum Chem 109: 385-400, 2009