We analyze the effect of increasing charge density on the Fixed Node Errors in Diffusion Monte Carlo by comparing FN-DMC calculations of the total ground state energy on a 4 electron system done with a Hartree-Fock based trial wave function to calculations by the same method on the same system using a Configuration Interaction based trial wave function. We do this for several different values of nuclear charge, Z. The Fixed Node Error of a Hartree-Fock trial wave function for a 4 electron system increases linearly with increasing nuclear charge.
@article{arxiv.1107.3520,
title = {Impact of the Electron Density on the Fixed-Node Errors in Quantum Monte Carlo},
author = {Kevin Rasch and Lubos Mitas},
journal= {arXiv preprint arXiv:1107.3520},
year = {2013}
}