Temperature and pressure dependence of intrinsic anharmonic and quantum corrections to the equation of state

Results of detailed calculations of the anharmonic and the quantum corrections to the equation of state and to Grüneisen's parameter γ are given for pressures P from zero to 2B0 (where B0 is the bulk modulus at P = 0 and T = 0) and for temperatures T from zero to (0.6) Tε (where Tε = ∈/k,∈ is the depth of the potential well and k is Boltzmann's constant). Interionic potentials of the form A/r+ϕR with ϕR proportional to r−12, r−8, and e−αr were used. It was found, for example, that at T = (0.2) T∈ the anharmonic corrections to P for the potentials in the order just given were approximately 7, 6, and 4% at P = (0.1)B0, while they were approximately 1, 1, and ½% at P = (0.5)B0. Quantum corrections to P were found to depend very weakly on P and to be about 1% or less for (0.2)B0 < P < 2B0 for temperatures above the zero‐pressure Debye temperature. Anharmonic corrections decreased the values of γ and of P, while quantum corrections decreased the value of γ but increased the value of P.