Optimized Exchange and Correlation Semilocal Functional for the Calculation of Energies of Formation

We present a semiempirical exchange-correlation functional for density functional theory tailored to calculate energies of formation of solids. It has the same form of a Perdew Burke Emzerhof functional, but three parameters have been fitted to reproduce experimental energies of formation of a representative set of binaries. The quality of the obtained functional has then been assessed for a control set of binary and ternary compounds. Our functional succeeds in reducing the error of the Perdew Burke Emzerhof generalized gradient approximation for energies of formation by a factor of 2. Furthermore, this result is athieved preserving the quality of the optimized geometry.