First Principles Methods: A Perspective From Quantum Monte Carlo

Quantum Monte Carlo methods are the most accurate algorithms for predicting properties of general quantum systems. We briefly introduce ground state, path integral at finite temperature and coupled-electron Monte Carlo methods, their merits and limitations. We then discuss recent calculations using these methods for dense liquid hydrogen as in undergoes a molecular atomic (metal/insulator) transition. We then discuss a procedure that can be used to assess electronic density functionals, which in turn can be used on a larger scale for first principles calculations and apply this technique to dense hydrogen and liquid water.