A calculation scheme for the pair-density functional theory for the superconductor

The pair-density functional theory for the superconductor (SC-PDFT) is one of first-principles theories for the superconductor. The feature of the SC-PDFT is that the fluctuation of the particle number of the superconducting state can be reproduced via the pair-density (PD) and electron density (ED). In this paper, we present a calculation scheme for the SC-PDFT. Specifically, in order to construct a calculation scheme, the searching region for PDs and EDs is devised with a reference to results of the uniform system, and the entropy functional is developed in a functional form in terms of the PD and ED. (author)