Variational Hartree‐Fock Calculations of the Ground State Energy of Metallic Hydrogen

The ground state energy of metallic hydrogen is calculated by a variational method in the Hartree‐Fock approximation. The periodic wave functions are taken to be a linear combination of Slatertype orbitals and k‐dependent and the exchange energy is treated exactly. Then it is shown that the inclusion of correlation effects, in the same approximation of the Kohn‐Sham equation, does not modify the result appreciably. The introduction of additional parameters confirms the previous results except those obtained by density functional method.