Hartree-Fock Lattice Constant and Bulk Modulus of Diamond

The equilibrium lattice constant and bulk modulus of diamond are calculated in the Hartree-Fock approximation to be 3.545 Å and 4.38 × ${10}^{12}$ dyn/${\mathrm{cm}}^2$, respectively. These values compare very well with the experimental values of 3.567 Å and 4.42 × ${10}^{12}$ dyn/${\mathrm{cm}}^2$. A comparison of the bulk modulus obtained from the pressure-volume product and from the total energy is made. The results are compared with other calculations which use local-density exchange operators. In addition, a new procedure for handling the two-electron integrals is presented with a computational test of the method.