Fixed-node quantum Monte Carlo calculation of static susceptibilities

Saverio Moroni
Istituto Officina dei Materiali, CNR, and SISSA, Trieste, Italie.

Mercredi 23 Octobre 2013, 11^h00
bibliothèque LCT, tour 12 - 13, 4e étage

We describe a method to compute derivatives of the fixed-node energy in a consistent way, i.e. with no other bias than the fixed-node approximation. It features
(i) a path-integral Metropolis method instead of a branching random walk,
(ii) a short-time approximation to the propagator which is better behaved near the nodes than the usual drift-diffusion Green's function, and
(iii) an extension of the so-called space-warp transformation to deal with the displacement of the nodes. We present illustrative results for the harmonic frequency of Li₂ and the static susceptibility of the electron gas.