Equation of state and raman frequency of diamond from quantum Monte Carlo simulations

We report variational and diffusion quantum Monte Carlo (VMC and DMC) calculations of the equation of state and Raman frequency of diamond. The pressure derivative of the bulk modulus, which has not been accurately determined experimentally, is calculated to be 3.8 (VMC) and 3.7 (DMC). The values of the Raman frequency calculated at the experimental volume are 1373 cm(-1) (VMC) and 1359 cm(-1) (DMC), in good agreement with the experimental value of 1333 cm(-1).