Optimization of ground and excited state wavefunctions and van der Waals   clusters
  A quantum Monte Carlo method is introduced to optimize excited state trial wavefunctions. The method is applied in a correlation function Monte Carlo calculation to compute ground and excited state energies of bosonic van der Waals clusters of upto seven particles. The calculations are performed using trial wavefunctions with general three-body correlations. 
M. P. Nightingale and Vilen Melik-Alaverdian