Variational Monte Carlo Calculations for Spin-Aligned Deuterium

The first variational Monte Carlo calculations of the ground-state energy of spin-aligned deuterium D↓ are presented. Using Slater-Jastrow trial wave functions, the calculations are based on the accurate theoretical pair potential of Kolos and Wolniewicz for the $b{{}_{}{}^3{}_{}{}^{}\Sigma _{\mathrm{u}}^{}{}_{}{}^{}}^{+}$ state. For D↓ with equal population of the three nuclear-spin states, the minimum theoretical ground-state energy is found to be negative, implying that this system is a liquid at zero temperature under zero external pressure.