Calculates the electronegativity contribution to the gamma factor in the Miedema model of mixing enthalpy. See equation 1 of: http://dx.doi.org/10.1016/j.cpc.2016.08.013

Parameters:¶

element_a: str¶

The periodic table symbol of element A

element_b: str¶

The periodic table symbol of element B

P: Number¶

An empirical factor dependent on the kinds of elements being mixed. P=14.1 for two transition metals, P=10.7 for two non-transition metals, and P=12.35 for one of each kind.