Electron-Vibration Coupling Calculation

Overview

MOMAP is capable of electron-vibration coupling (EVC) calculation aiming to analyze Duschinsky rotation and normal mode vibrations, which is based on evc subprograms. [1]

In the following part, this kind of calculation will be called evc calculation.

evc can receive outputs from other QC programs, such as Gaussian, TURBOMOLE, ChemShell, Dalton, MOLPRO, DFTB and MOPAC. It can also read data from the output files, including vibrational frequencies and force constant matrix, and calculate normal mode displacement, Huang-Rhys factor, reorganization energy and Duschinsky rotation matrix between initial and final electronic states under both internal coordinate and cartesian coordinate.

Start running calculation

evc calculation requires basic information about initial and final electronic states. So to start a evc calculation, you need to designate the file names in the evc input file (evc.inp).

Here is an example of the simplest evc input file. For Gaussian output files, you have to provide the corresponding *.fchk files as well. See /example/DSB/evc for more information.

&evc
  ffreq(1)  = "Groundstate_vibration.log"
  ffreq(2)  = "Excitedstate_vibration.log"
/

After creating your own evc input file, run bin/evc evc.inp to run the calculation.

Other examples are provided in the following directories:

examples/DSB/evc examples/6T/evc examples/azulene/evc

These examples also contain a run file, which includes the location of evc program and the command of running calculation. Users can simply modify this file and perform the calculation via a single command ./run.

Except for ffreq(1) and ffreq(2) parameters, evc program also allows users to project reorganization energy onto the internal coordinate, consider isotope effect and configure many other advanced settings.

To change the settings and start your own evc calculation using advanced settings, please refer to examples/6T/evc/evc.inp for further information.

Program outputs

The main results that obtained from this calculation are the properties between initial and final electronic states - normal mode displacement, Huang-Rhys factor, reorganization energy and Duschinsky rotation matrix. The information is kept in evc.cart.dat and evc.dint.dat.

  1. evc.cart.dat Use Cartesian coordinate to calculate the properties above.
  2. evc.dint.dat Use internal coordinate to calculate normal mode displacement, Huang-Rhys factor and reorganization energy, while using Cartesian coordinate to calculate Duschinsky rotation matrix.

Please check reorganization energy results between evc.cart.dat and evc.dint.dat. If the energy difference is small (< 1000 cm-1), then use the results in evc.cart.dat to proceed the next calculations. However, if the energy difference is big, then use evc.dint.dat to proceed the next calculations.

[1]evc program is recreated from dushin program, which is written by Prof. Jeffrey R. Reimers (J. Chem. Phys. vol. 115, 9103-9109, 2001)