The α→β transition (tin pest) in tin is of great importance for all Sn-rich alloys, since the occurrence of this phase transformation has detrimental effects on their properties. Experimentally it has been found that this transition occurs at 13°C. Alloys are based on the high-temperature body-centered tetragonal β phase (white tin), while the low temperature α phase has a diamond-type crystal structure.
In this work we investigate the effect of vibrational entropy and pressure on the transition temperature, using Density-Functional-Theory (DFT) and Density-Functional-Perturbation-Theory (DFPT). The difference in energy between the α and β phases is of the order of 20 meV according to experimental estimates, which is at the limit of DFT accuracy. We analyze the effect different exchange-correlation functionals and pseudopotentials on the transition temperature. The results are systematically compared with available experimental values.