Cooper Pairs Distribution function for bcc Niobium under pressure from first-principles

In this paper, we report Cooper Pairs Distribution function [Formula: see text] for bcc Niobium under pressure. This function reveals information about the superconductor state through the determination of the spectral regions for Cooper-pairs formation. [Formula: see text] is built from the well-established Eliashberg spectral function and phonon density of states, calculated by first-principles. [Formula: see text] for Nb suggests that the low-frequency vibration region [Formula: see text] is where Cooper-pairs are possible. From [Formula: see text] , it is possible to obtain the [Formula: see text] parameter, which is proportional to the total number of Cooper-Pairs formed at a temperature [Formula: see text] . The [Formula: see text] parameter allows an approach to the understanding of the Nb [Formula: see text] anomalies, measured around 5 and 50 GPa.