needs BoltzTrap2 | TU Wien or TransOpt with VASP. There are tutorials come with their software.

Dr. W

You can use equations to calculate the effective mass of electrons. There are several videos on YouTube.

1. https://youtu.be/QeM-YKEn74g?si=RI_LQClsFXuS8Xl-

2. https://youtu.be/t3jqIVnRR-U?si=iikVe2mhZgQ0VJfn

To calculate the effective mass in VASP after obtaining the band structure with the hybrid HSE06 functional, you'll need to extract the band structure data near the conduction band minimum (CBM) or valence band maximum (VBM) from the EIGENVAL or PROCAR files. Use a dense k-point mesh to ensure accuracy, then fit the band structure around the CBM or VBM to a parabolic function E(k)=ℏ2k22m∗E(k)=2m∗ℏ2k2​. The effective mass m∗m∗ is derived from the curvature of this fit, specifically using the second derivative of energy with respect to the wavevector kk. You can perform this fitting and derivative calculation using Python libraries like numpy and scipy, or use specialized tools like sumo or Effmass for a more automated approach.