Simplification of total-energy and pressure calculations in solids

In addition to presenting an expression for the pressure which is valid for all treatments of exchange and correlation, we derive a new relation for the kinetic energy of the cores which, in the muffin-tin approximation, leads to an algebraic cancellation of various core contributions to the pressure. Thus, numerical difficulties associated with total-energy and pressure calculations are greatly reduced. © 1974 The American Physical Society.