Abstract
The self-healing diffusion Monte Carlo algorithm (SHDMC) [Phys. Rev.
B {\bf 79} 195117 (2009), {\it ibid.} {\bf 80} 125110 (2009)] is
applied to the calculation of ground state states of atoms and
molecules. By direct comparison with accurate configuration
interaction results we show that applying the SHDMC method to the
oxygen atom leads to systematic convergence towards the exact ground
state wave function. We present results for the small but
challenging N$_2$ molecule, where results obtained
via the energy minimization method and SHDMC are within
experimental accuracy of 0.08 eV.
Moreover, we demonstrate that the algorithm is robust enough to be
used for the calculations of systems at least as large as C$_{20}$
starting from a set of random coefficients. SHDMC thus constitutes
a practical method for systematically reducing the fermion sign
problem in electronic structure calculations.
