Energy and pressure versus volume: Equations of state motivated by the stabilized jellium model - art. no. 224115

Explicit functions are widely used to interpolate, extrapolate, and differe ntiate theoretical or experimental data on the equation of state (EOS) of a solid. We present two EOS functions which are theoretically motivated. The simplest realistic model for a simple metal, the stabilized jellium (SJ) o r structureless pseudopotential model, is the paradigm for our SJEOS. A sim ple metal with exponentially overlapped ion cores is the paradigm for an au gmented version (ASJEOS) of the SJEOS. For the three solids tested (Al, Li, Mo), the ASJEOS matches all-electron calculations better than prior equati ons of state. Like most of the prior EOS's, the ASJEOS predicts pressure P as a function of compressed volume v from only a few equilibrium inputs: th e volume v(o), the bulk modulus B-o, and its pressure derivative B-1. Under expansion, the cohesive energy serves as another input. A further advantag e of the new equation of state is that these equilibrium properties other t han vo may be found by linear fitting methods. The SJEOS can be used to cor rect B-o and the EOS found from an approximate density functional, if the c orresponding error in v(o) is known. We also (a) estimate the typically sma ll contribution of phonon zero-point vibration to the EOS, ib) find that th e physical hardness By does not maximize at equilibrium, and (c) show that the "ideal metal'' of Shore and Rose is the zero-valence limit of stabilize d jellium.