Rn. Barnett et al., FIXED-SAMPLE OPTIMIZATION IN QUANTUM MONTE-CARLO USING A PROBABILITY DENSITY-FUNCTION, Chemical physics letters, 273(5-6), 1997, pp. 321-328
We consider parameter optimization for trial functions to be used for
fixed-node diffusion Monte Carlo. By employing sample points selected
from a positive definite distribution, parameters that determine the n
odes of the trial function can be varied with no loss of stability and
without sample bias. With CH as a test system, our optimized trial fu
nction gives a fixed-node energy lying below that of a MCSCF trial fun
ction with the same number of determinants and the same basis set. The
present approach sheds light on the important question of how to impr
ove the nodal structure and, thereby, the accuracy of diffusion Monte
Carlo. (C) 1997 Elsevier Science B.V.