Have you considered the lattice vibration (phonon) contribution? You need different atomic positions at different temperatures to include the phononic effect.
Best M J Hasan Mechanical Engineering University of Maine On Tue, Aug 13, 2024 at 8:17 AM David Fernandes Machado <[email protected]> wrote: > Hello all, > > > > I am trying to determine the dependence of the energy gap of silicon as a > function of temperature. In the literature, it is stated that the decrease > in the energy gap of silicon with increasing temperature can be explained > by thermal expansion and electron-phonon interaction. > > > > First, I used the *thermo_pw* library (which uses the QHA approximation) > to determine the lattice parameter of silicon as a function of temperature. > Then, I ran the following calculations: SCF, NSCF, DOS, band, and finally > plotband. I performed these calculations using the lattice parameters of Si > corresponding to temperatures in a range from 4K to 800K. For this > simulation, I am using PBE pseudopotentials, an ecutwfc of 25 Ry, and a > unit cell with 2 atoms. > > > > The problem is that the gap increases with temperature instead of > decreasing. I obtained a gap of 0.6187 eV at 4K and 0.6315 eV at 800K. > > > > I also tried calculating the band structure considering electron-phonon > coupling using the EPW library, but the gap still increases with > temperature. > > > > Has anyone already tried to calculate the silicon gap as a function of > temperature? What am I doing wrong? > _______________________________________________ > The Quantum ESPRESSO community stands by the Ukrainian > people and expresses its concerns about the devastating > effects that the Russian military offensive has on their > country and on the free and peaceful scientific, cultural, > and economic cooperation amongst peoples > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
