Table of Contents
Which basis sets and/or pseudopotentials should I use?
When in doubt, always use the
DZVP-MOLOPT-GTH basis set and the
In some cases (for example for tin) there is only a short-range basis set available, called
You can find all available MOLOPT basis sets in
BASIS_MOLOPT, which is located in the folder
$CP2K_DATA_DIR (after loading the CP2K module).
How do I run CP2K in parallel?
cp2k.sopt is the single-process variant of CP2K.
To run CP2K in parallel, you have to use a different executable named
cp2k.popt and prefix that with
mpirun -n 8 to run it on 8 CPUs in parallel. So, a complete command line to run CP2K on 8 CPUs would then be:
$ mpirun -n 8 cp2k.popt -i yourinput.inp -o youroutput.out
How do I obtain a charge density difference?
In Exercise 2 a series of
*.cube files was already produced for MOs.
To obtain the electronic charge density in a
*.cube, file the following snippet of input file can be used (see also the reference manual):
&FORCE_EVAL &DFT &PRINT &E_DENSITY_CUBE &END E_DENSITY_CUBE ... &END PRINT ... ... &END DFT &END FORCE_EVAL
The cubecruncher tool can be used to obtain charge density differences. A precompiled executable is available on the server
tcopt3, its path being
The basic usage to obtain a charge density difference is:
$ /users/scaravat/bin/cubecruncher.x -i input.cube -o output.cube -subtract subsystem.cube
How do I build a slab model for a surface?
E.g. by using VESTA. A tutorial is available here.
Vesta comes preinstalled on
tcopt3, provided that you load the proper module.
$ module load vesta
How do I obtain the stress tensor?
You have to add the following snippet to the input file:
&FORCE_EVAL ... STRESS_TENSOR ANALYTICAL &PRINT &STRESS_TENSOR &END STRESS_TENSOR &END PRINT ... &END FORCE_EVAL
RUN_TYPE ENERGYwon't work!
My calculation does not converge
... and I use MULTIPLE_UNIT_CELL
- first make sure that you actually need
MULTIPLE_UNIT_CELL. In case you want to do band structure calculation, you most definitely do not want it
- if you are sure that you need it, make sure that it is specified two times: once in the ''CELL'' section and a second time in the ''TOPOLOGY'' section, otherwise your calculation may or may not converge