DFT + GWBSE Optimization Using CO¶
Introduction¶
This tutorial explains how to perform a molecular geometric optimization using the GWBSE method. See the GW Compendium: A Practical Guide to Theoretical Photoemission Spectroscopy, for an excellent introduction to the method.
Requirements¶
You will need to install VOTCA using the instructions described here
Once the installation is completed you need to activate the VOTCA enviroment by running the
VOTCARC.bash
script that has been installed at the bin subfolder for the path that you have provided for the installation step above
Preparing the input¶
To run a DFT-GWBSE calculation we will use the xtp_tools calculator.
we can now change the calculator mode from single point energy calculation to optimization as follows by adding -c geometry_optimization.maxiter=1
which enables optimization with one iteration.
Because geometry optimsation is quite expensive numerically we chose a smaller basisset and G0W0 Finally, to run the calculation we just need the following command (This still takes a while)
[1]:
!xtp_tools -c job_name=CO geometry_optimization.maxiter=1 dftpackage.basisset=3-21G dftpackage.auxbasisset=aux-def2-svp gwbse.gw.mode=G0W0 -e dftgwbse -t 4
/bin/bash: line 1: xtp_tools: command not found
Notice that we are using 4 threads. The results will be stored in a file named CO_summary.xml
in the current work directory, together with the optimization step in optimisation.trj
and the orbitals in hdf5 format saved on CO.orb
.