Abstract
In view of the continuous theoretical efforts
aimed at an accurate microscopic description of the strongly
correlated transition metal oxides and related materials,
we show that with continuum quantum Monte Carlo (QMC) calculations it is possible to
obtain the value of the spin superexchange coupling constant of a copper
oxide in a quantitatively
excellent agreement with experiment. The variational nature
of the QMC total energy allows us to identify the best
trial wave function out of the available pool of wave functions, which
makes the approach essentially free from adjustable parameters
and thus truly ab initio. The present results on magnetic interactions
suggest that QMC is capable of accurately describing ground state
properties of strongly correlated materials.
