CA-NAC

Concentric Approximation - Nonadiabatic Coupling

is a code base to accurately and efficiently evaluate nonadiabatic coupling (NAC), a crucial quantity in nonadiabatic molecular dynamics (NAMD), under the PAW formalism. Specifically, it's used to extract the planewave coefficients from VASP pseudo-wavefunction file WAVECAR and PAW projector coefficients from VASP projector file NORMALCAR(optional) to calculate pseudo-NAC (PS-NAC) and exact-NAC AKA "all-electron" under PAW (AE-NAC). In addition, other advanced techniques like phase correction and state reordering are also implemented in this code.

Prerequisites

• Python3
• ASE
• Scipy
• Numpy
• VaspBandUnfolding [https://github.com/QijingZheng/VaspBandUnfolding]
• (Optional）For AE-NAC only，you need to modify VASP source code slightly and recompile it. The original part in VASP is not coded properly. A patch is available upon request by email (Please make sure you have legal access to VASP)

Known issues

1. For AE-NAC only, currently, it does not support the NORMALCAR that is generated with gamma-only version VASP. Alternatively, you can use standard verision VASP to generate WAVECAR and NORMALCAR with only one gamma point in KPOINTS.

Reference

Citation is much appreciated. 👍

• Main CA-NAC paper

  Concentric Approximation for Fast and Accurate Numerical Evaluation of Nonadiabatic Coupling with Projector Augmented-Wave Pseudopotentials

  Weibin Chu and Oleg V. Prezhdo

  The Journal of Physical Chemistry Letters 2021 12 (12), 3082-3089

• Evaluation of AE-NAC and PS-NAC. PS-NAC fails in the system with transition metal

  Accurate Computation of Nonadiabatic Coupling with Projector Augmented-Wave Pseudopotentials

  Weibin Chu, Qijing Zheng, Alexey V. Akimov, Jin Zhao, Wissam A. Saidi, and Oleg V. Prezhdo

  The Journal of Physical Chemistry Letters 2020 11 (23), 10073-10080