[CP2K-user] [CP2K:21450] DDEC6 Charges, Valence Density Mismatch
Nicholas Laws
nicholaslaws8 at gmail.com
Wed May 7 17:48:17 UTC 2025
Hi CP2K Community,
I am trying to obtain time-dependent DDEC6 charges for a mixed QM/MM
simulation in which an EMI-BF4 ion pair (76 valence e, 26 core e) collides
with a gold slab at various kinetic energies. The QM region is treated with
ωB97X-V/aug-cc-pVTZ and all-electron potentials in GAPW. During production
(input *ESC**ollision.inp**,* attached) I print a cube with:
&PRINT
&E_DENSITY_CUBE
DENSITY_INCLUDE SOFT_DENSITY
NGAUSS 0
STRIDE 1 1 1
FILENAME valence_density
&END
&END
and a 5-level PW grid of:
&MGRID
NGRIDS 5
CUTOFF 800
REL_CUTOFF 80
COMMENSURATE .TRUE.
&END
The log shows:
Electronic density on regular grids: -76.7658266487
25.2341733513
Core density on regular grids: 102.0000000000
-0.0000000000
Hard and soft densities (Lebedev): -694.5370264067
-669.3028566617
Total Rho_soft + Rho1_hard - Rho1_soft -101.9999963937
Total charge density (r-space): 0.0000036063
Total Rho_soft + Rho0_soft (g-space): 0.0000033449
Overlap energy of the core charge distribution:
0.00002215241243
Self energy of the core charge distribution:
-720.29674329623936
Core Hamiltonian energy:
-75.86850888340894
Hartree energy:
209.46847518535864
Exchange-correlation energy:
-26.02788481604846
Hartree-Fock Exchange energy:
-28.87249823090302
Dispersion energy:
0.25782644744755
so the cube integrates to ≈77 e instead of the expected 76 e. Chargemol
therefore exits with
ncore = 26.0000
nvalence = 76.0000
pixelvolume = 1.3079E-03
numerically integrated valence density = 7.6767E+01
sum_valence_occupancy_correction = 0.0000E+00
checkme = 7.6659E-01
The electrons are not properly accounted for. Either the grid in your
electron density input file is too coarse, you have specified the incorrect
net charge in the chargemol_job.m file, or the number of core electrons for
each atom has not been set up correctly.
Program will terminate.
My questions are:
1.
Is there any keyword combination in GAPW that prints only the valence
density (ρ_soft + ρ₁,hard − ρ₁,soft) so the integral matches 76 e, or must
I run a GPW single-point for every MD frame?
2.
Is there a published benchmark for the PW cutoff required to converge
ωB97X-V + aug-cc-pVTZ?
Any hints, keywords, code pointers, or literature would be greatly
appreciated!
Many thanks in advance,
Nick
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