Variational Monte-Carlo calculations of 3He droplets

During 1984 the Feynman-Cohen backflow correlation was included in the authors variational Monte Carlo program for Fermion droplets. With this correlation every element of the Slater determinant is changed when just one atom is moved. This makes the evaluation of the modified wavefunction and of the kinetic energy much more time-consuming. The authors attempted to reduce the computational requirements by omitting the backflow from the random walk and by using the simpler Clark-Westhaus form for the backflow kinetic energy; in both cases the resulting increase in the variance was unacceptably large. Therefore this program now controls the random walk with the backflow correlation and uses the Pandharipande-Bethe kinetic energy