Phonon Renormalizations of Vertical Excitation Energies

For this tutorial we will use Quantum Espresso as a DFT solver and WEST code for TDDFT calculations.

The ground state phonon were precomputed using finite displacement method using PhonoPy Code. Note, it could also be performed using PyEPFD, as we did in exercise 1.1. However, the NV-center has a C_3v symmetry, which PhonoPy can exploit to reduce number of DFT single-point calculations needed for obtaining the phonon modes. Currently, phonon calculations using PyEPFD cannot exploit symmetry.

After obtaining the phonon modes we would compute the stochastic displacements and perform DFT and TDDFT calculations using QE and WEST code.

Lets get started.

• 2.1 PhonoPy to PyEPFD conversion
• 2.2 Generating Stochastically Displaced Configurations
• 2.3 Converting XYZ files into a Quantum Espresso Input Deck
• 2.4 Phonon Renormalizations Single-Particle Levels
• 2.5 Phonon Renormalizations of Many-Body States