[CP2K-user] [CP2K:14965] odd force drift convergence with respect to density cutoff
hut... at chem.uzh.ch
hut... at chem.uzh.ch
Thu Mar 18 16:23:15 UTC 2021
Hi
there are two sources of errors that could be relevant for this.
1) by changing the cutoff, the relative position of the atoms within
the real space grids change. This then leads to a change of
energy and forces. This has been discussed before here.
2) By default you are using multiple grids and by changing the
cutoff, the change in accuracy is not linear but might jump
at certain cutoffs.
best regards
Juerg Hutter
--------------------------------------------------------------
Juerg Hutter Phone : ++41 44 635 4491
Institut für Chemie C FAX : ++41 44 635 6838
Universität Zürich E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------
-----cp... at googlegroups.com wrote: -----
To: "cp2k" <cp... at googlegroups.com>
From: "W. Lai"
Sent by: cp... at googlegroups.com
Date: 03/18/2021 03:11PM
Subject: [CP2K:14965] odd force drift convergence with respect to density cutoff
Dear CP2k users and developers,
I am seeing odd behavior on how force drift(error) change as we change the density cutoff value (from 400 to 1600 Ry), for a model material of SiC-6H. I am using the 7.1 version and I changed the force error ("Sum of Atomic Forces") to eV/A.
While it is subjective to consider what is an acceptable value for the force error (i.e. 0.01 or 0.001 eV/A), such oscillation really makes it a difficult task to choose the appropriate cutoff.
It is worth noting this is a hexagonal cell and force error is primarily on the z direction. Input file is enclosed.
Thanks, Wei
&GLOBAL
PROJECT SiC
RUN_TYPE ENERGY_FORCE
PRINT_LEVEL LOW
&END GLOBAL
&FORCE_EVAL
STRESS_TENSOR ANALYTICAL
METHOD QS
&DFT
BASIS_SET_FILE_NAME BASIS_MOLOPT
POTENTIAL_FILE_NAME GTH_POTENTIALS
&MGRID
CUTOFF 400
REL_CUTOFF 60
&END MGRID
&QS
METHOD GPW
EPS_DEFAULT 1.0E-12
&END QS
&SCF
SCF_GUESS ATOMIC
MAX_SCF 100
EPS_SCF 5.0E-8
ADDED_MOS 60
CHOLESKY INVERSE
&SMEAR ON
METHOD FERMI_DIRAC
ELECTRONIC_TEMPERATURE [K] 300
&END SMEAR
&DIAGONALIZATION
&END DIAGONALIZATION
&MIXING
METHOD BROYDEN_MIXING
ALPHA 0.2
&END
&PRINT
&RESTART OFF
&END
&END
&END SCF
&XC
&XC_FUNCTIONAL PBE
&END XC_FUNCTIONAL
&END XC
&POISSON
PERIODIC XYZ
&END
&PRINT
&E_DENSITY_CUBE OFF
&EACH
MD 10
&END EACH
STRIDE 1 1 1
&END E_DENSITY_CUBE
&END PRINT
&END DFT
&SUBSYS
&KIND Si
ELEMENT Si
BASIS_SET DZVP-MOLOPT-SR-GTH
POTENTIAL GTH-PBE
&END KIND
&KIND C
ELEMENT C
BASIS_SET DZVP-MOLOPT-SR-GTH
POTENTIAL GTH-PBE
&END KIND
&CELL
PERIODIC XYZ
A 9.2430000305 0.0000000000 0.0000000000
B -4.6215010811 8.0046722182 0.0000000000
C 0.0000000000 0.0000000000 15.1247997284
&END CELL
&COORD
Si 0.0 0.0 0.0
Si -1.5405004 2.6682241 0.0
Si -3.0810008 5.3364482 0.0
Si 3.0810001 0.0 0.0
Si 1.5404997 2.6682241 0.0
Si -7.1525574e-07 5.3364482 0.0
Si 6.1620002 0.0 0.0
Si 4.6215 2.6682241 0.0
Si 3.0809994 5.3364482 0.0
Si 0.0 0.0 7.5623999
Si -1.5405004 2.6682241 7.5623999
Si -3.0810008 5.3364482 7.5623999
Si 3.0810001 0.0 7.5623999
Si 1.5404997 2.6682241 7.5623999
Si -7.1525574e-07 5.3364482 7.5623999
Si 6.1620002 0.0 7.5623999
Si 4.6215 2.6682241 7.5623999
Si 3.0809994 5.3364482 7.5623999
Si -1.1920929e-07 1.7788159 2.5208001
Si -1.5405003 4.4470396 2.5208001
Si -3.0810008 7.1152635 2.5208001
Si 3.0810001 1.7788159 2.5208001
Si 1.5405 4.4470396 2.5208001
Si -4.7683716e-07 7.1152635 2.5208001
Si 6.1619997 1.7788159 2.5208001
Si 4.6215 4.4470396 2.5208001
Si 3.0809994 7.1152635 2.5208001
Si 1.5405 0.889408 10.0832005
Si -4.7683716e-07 3.5576318 10.0832005
Si -1.5405007 6.2258563 10.0832005
Si 4.6215 0.889408 10.0832005
Si 3.0809999 3.5576318 10.0832005
Si 1.5404995 6.2258563 10.0832005
Si 7.7025004 0.889408 10.0832005
Si 6.1620002 3.5576318 10.0832005
Si 4.621501 6.2258563 10.0832005
Si 1.5405001 0.889408 5.0350456
Si -2.3841858e-07 3.5576318 5.0350456
Si -1.5405004 6.2258563 5.0350456
Si 4.6215 0.889408 5.0350456
Si 3.0809999 3.5576318 5.0350456
Si 1.5404995 6.2258563 5.0350456
Si 7.7025004 0.889408 5.0350456
Si 6.1620002 3.5576318 5.0350456
Si 4.621501 6.2258563 5.0350456
Si -2.3841858e-07 1.7788158 12.5974455
Si -1.5405004 4.4470396 12.5974455
Si -3.0810008 7.1152635 12.5974455
Si 3.0810003 1.7788158 12.5974455
Si 1.5405 4.4470396 12.5974455
Si -4.7683716e-07 7.1152635 12.5974455
Si 6.1619997 1.7788158 12.5974455
Si 4.6215 4.4470396 12.5974455
Si 3.0809994 7.1152635 12.5974455
C -1.1920929e-07 1.7788159 0.6231418
C -1.5405003 4.4470396 0.6231418
C -3.0810008 7.1152635 0.6231418
C 3.0810001 1.7788159 0.6231418
C 1.5405 4.4470396 0.6231418
C -4.7683716e-07 7.1152635 0.6231418
C 6.1619997 1.7788159 0.6231418
C 4.6215 4.4470396 0.6231418
C 3.0809994 7.1152635 0.6231418
C 1.5405 0.889408 8.1855412
C -4.7683716e-07 3.5576318 8.1855412
C -1.5405007 6.2258563 8.1855412
C 4.6215 0.889408 8.1855412
C 3.0809999 3.5576318 8.1855412
C 1.5404995 6.2258563 8.1855412
C 7.7025004 0.889408 8.1855412
C 6.1620002 3.5576318 8.1855412
C 4.621501 6.2258563 8.1855412
C 1.5405001 0.889408 3.1459584
C -2.3841858e-07 3.5576318 3.1459584
C -1.5405004 6.2258563 3.1459584
C 4.6215 0.889408 3.1459584
C 3.0809999 3.5576318 3.1459584
C 1.5404995 6.2258563 3.1459584
C 7.7025004 0.889408 3.1459584
C 6.1620002 3.5576318 3.1459584
C 4.621501 6.2258563 3.1459584
C -2.3841858e-07 1.7788158 10.7083578
C -1.5405004 4.4470396 10.7083578
C -3.0810008 7.1152635 10.7083578
C 3.0810003 1.7788158 10.7083578
C 1.5405 4.4470396 10.7083578
C -4.7683716e-07 7.1152635 10.7083578
C 6.1619997 1.7788158 10.7083578
C 4.6215 4.4470396 10.7083578
C 3.0809994 7.1152635 10.7083578
C 0.0 0.0 5.6657501
C -1.5405004 2.6682241 5.6657501
C -3.0810008 5.3364482 5.6657501
C 3.0810001 0.0 5.6657501
C 1.5404997 2.6682241 5.6657501
C -7.1525574e-07 5.3364482 5.6657501
C 6.1620002 0.0 5.6657501
C 4.6215 2.6682241 5.6657501
C 3.0809994 5.3364482 5.6657501
C 0.0 0.0 13.2281494
C -1.5405004 2.6682241 13.2281494
C -3.0810008 5.3364482 13.2281494
C 3.0810001 0.0 13.2281494
C 1.5404997 2.6682241 13.2281494
C -7.1525574e-07 5.3364482 13.2281494
C 6.1620002 0.0 13.2281494
C 4.6215 2.6682241 13.2281494
C 3.0809994 5.3364482 13.2281494
&END COORD
&END SUBSYS
&PRINT
&FORCES ON
&END FORCES
&TOTAL_NUMBERS ON
&END TOTAL_NUMBERS
&END PRINT
&END FORCE_EVAL
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