Ab Initio Study Of Lattice Dynamics Of Group Iv Semiconductors Using Pseudohybrid Functionals For Extended Hubbard Interactions

We study the lattice dynamics of group IV semiconductors using the fully ab initio extended Hubbard functional. The on-site and intersite Hubbard interactions are determined self-consistently with recently developed pseudohybrid functionals and included in force calculations. We analyze the Pulay forces with the choice of atomic orbital projectors and the force contribution of the on-site and intersite Hubbard terms. The phonon dispersions, Gruneisen parameters, and lattice thermal conductivities of diamond, silicon, and germanium, which are the most representative covalent-bonding semiconductors, are calculated and compared with the results using local, semilocal, and hybrid functionals. The extended Hubbard functional produces increased phonon velocities and lifetimes, and thus lattice thermal conductivities compared to local and semilocal functionals, agreeing with experiments very well. Considering that our computational demand is comparable to simple local functionals, this work thus suggests a way to perform high-throughput electronic and structural calculations with higher accuracy.