Explicitly correlated trial wave functions in Quantum Monte Carlo calculations of excited states of Be and Be-

摘要

We present a new form of explicitly correlated wave function whose parametersare mainly linear, to circumvent the problem of the optimization of a largenumber of non-linear parameters usually encountered with basis sets ofexplicitly correlated wave functions. With this trial wave function wesucceeded in minimizing the energy instead of the variance of the local energy,as is more common in quantum Monte Carlo methods. We applied this wave functionto the calculation of the energies of Be 3P (1s22p2) and Be- 4So (1s22p3) byvariational and diffusion Monte Carlo methods. The results compare favorablywith those obtained by different types of explicitly correlated trial wavefunctions already described in the literature. The energies obtained areimproved with respect to the best variational ones found in literature, andwithin one standard deviation from the estimated non-relativistic limits