# [CP2K-user] [CP2K:16557] How to use ECP potential in FORCE_EVAL

Eugene roginovicci at gmail.com
Mon Feb 7 16:30:10 UTC 2022

```According to cp2k documentation
https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/SUBSYS/KIND.html#POTENTIAL it
is possible to set POTENTIAL variable value as ECP, in order to use
Effective core potential. I've converted basis set
from http://www.tc.uni-koeln.de/PP/clickpse.en.html according to CP2K
documentation. The section KIND in my input file is:

* &KIND VBASIS_SET STOLL-PBEPOTENTIAL ECP&POTENTIALV nelec 10V ul2
1.000000000            0.000000000      V S2     14.490000000
178.447971000      2      6.524000000           19.831375000      V P2
14.300000000          109.529763000      2      6.021000000
12.570310000      V D2     17.480000000          -19.219657000      2
5.709000000           -0.642775000      &END&END KIND*
The basis set in new file is:

*V STOLL-PBE 4 2  0  0  7  1  0 # Gauss type functions l=0 set 1 (3s
orbital)  12.8432080  0.460448  11.3757530 -0.495309   5.4069740 -0.350821
1.4659270  0.654979   0.5980800  0.582548   0.0887900  0.017081
0.0353180 -0.007455 2  0  0  7  1  0 **# Gauss type functions l=0 set 2
(4s orbital)*

*  12.8432080  0.126932  11.3757530 -0.139770  5.4069740  -0.089862
1.4659270   0.204669  0.5980800   0.321169  0.0887900  -0.657043  0.0353180
-0.474893 2  1  1  6  0  1 **# Gauss type functions l=1 set 1 (3p orbital)*

*  31.8898680  0.004658   8.2371780 -0.119249   4.3283730  0.125195
1.5405260  0.620704   0.5280810  0.416780   0.0899620  0.014015 2  2  2  5
1 **# Gauss type functions l=2 set 1 (3d orbital)*

*  22.6804330  0.031628   6.8613120  0.153807   2.2754450  0.378661
0.7319220  0.507276   0.2007460  0.275921*

CP2K starts normally but exit with error message:
*CPASSERT failed   qs_mo_types.F:295*
By checking source code I have error here:
*CPASSERT(nmo >= nomo)*

Could someone kindly give a working example for force calculations with ECP
potential.