Zero-Point Vacancy Concentration in a Model Quantum Solid: A Reversible-Work Approach

We investigate the influence of anharmonic effects on the zero-point vacancy concentration in a boson system model in the solid phase at T=0 K. We apply the reversible-work method to compute the vacancy formation free energy and the vacancy concentration in the system. A comparison of our results with those obtained using the harmonic approximation show that anharmonic effects reduce the formation free energy by similar to 25%, leading to an increase of the zero-point vacancy concentration by more than an order of magnitude.