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
Error after changing coordinates
If you get an error after copy and pasting coordinates from a website/service/other file into a CP2K input file and you get an error afterwards when trying to run it, please make sure that you are only using spaces as delimiters between the atomic kind and each of the coordinates.