Abstract
A suite of density functional theory (DFT) approaches that provide accurate and reliable superconductivity parameters without post-calculation corrections is presented. The sensitivity of phonon dispersion (PD) outputs to slight variations in calculation and external parameters enables identification of the most electron-coupled phonon mode(s). These mode(s) are directly linked, in a range of superconductors, to specific band structure characteristics and to the response of electrons to deformation potentials. These approaches are applied successfully to MgB(2)under a wide range of variable external conditions, including isotopic state, metal substitutions, pressure, and temperature. This approach has also been extended to other chemical systems with significantly different composition and crystal symmetry, such as YB6, H3S under pressure, B-doped diamond, B-doped silicon, and A15 compounds, to name a few. The effectiveness of these approaches that link both PDs and electronic band structures (EBSs) is largely dependent on reliable and accurate DFT results at the meV range that resolve Fermi surface (FS) detail in close reciprocal space proximity. Such a level of meV resolution is possible only by using extremely fine k-grids and large cutoff radii, much smaller and larger, respectively, to what has typically been used in DFT calculations reported in the literature.