[CP2K-user] [CP2K:17459] Different values of stress tensor from FORCE_EVAL and MOTION sections duing MD
Abhishek Sharma
asharma.ms.in at gmail.com
Thu Aug 11 09:44:59 UTC 2022
Many thanks Matthias for your reply
On Wed, Aug 10, 2022 at 4:04 PM Krack Matthias (PSI) <matthias.krack at psi.ch>
wrote:
> Hi Abhishek
>
>
>
> The total stress tensor including the contributions from the kinetic
> energy and the constraints (e.g. during a NpT run) is written to the
> .stress file whereas only the (zero-T) stress tensor is written to the CP2K
> output file, which are basically the derivatives of the total energy wrt to
> the cell parameters as needed during a CELL_OPT run.
>
>
>
> HTH
>
>
>
> Matthias
>
>
>
> *From: *"cp2k at googlegroups.com" <cp2k at googlegroups.com> on behalf of
> Abhishek Sharma <asharma.ms.in at gmail.com>
> *Reply to: *"cp2k at googlegroups.com" <cp2k at googlegroups.com>
> *Date: *Wednesday, 10 August 2022 at 16:12
> *To: *"cp2k at googlegroups.com" <cp2k at googlegroups.com>
> *Subject: *[CP2K:17456] Different values of stress tensor from FORCE_EVAL
> and MOTION sections duing MD
>
>
>
> Dear CP2K users,
>
>
>
> I am trying to monitor the stress tensor in my ab initio MD simulation in
> NPT ensemble using CP2K version 7.1. I wrote two print sections, one in
> FORCE_EVAL section (to print stress file) as
>
> ...
>
> &PRINT
> &FORCES ON
> FILENAME =forces
> &END FORCES
> &STRESS_TENSOR ON
> FILENAME =stress
> &END STRESS_TENSOR
> &END PRINT
> STRESS_TENSOR ANALYTICAL
>
>
>
> and another in PRINT of MOTION section (to get pressure file)
>
> ...
>
> &STRESS
> &EACH
> MD 1
> &END
> FILENAME pressure
> &END STRESS
>
>
>
> After running the job , I got following output in the stress file:
>
> STRESS TENSOR [GPa]
> X Y Z
> X 0.00106044 -0.00003023 -0.00393423
> Y -0.00003023 0.01251158 0.00014630
> Z -0.00393423 0.00014630 0.00717328
> 1/3 Trace(stress tensor): 6.91510096E-03
> Det(stress tensor) : -9.84767286E-08
> EIGENVECTORS AND EIGENVALUES OF THE STRESS TENSOR
> -0.00086519 0.00909269 0.01251781
>
> 0.89817098 -0.43935160 -0.01609565
> -0.00277868 -0.04228259 0.99910183
> 0.43963755 0.89731954 0.03919782
>
> ==============================================================================
> Stress Tensor Components (GPW/GAPW)
> 1/3 Trace
> Determinant
> Kinetic Energy Stress 1.22833622
> 0.02852337
> Basis Overlap Stress 0.30458944
> 0.01186246
> ES + XC Stress -1736.32537740
> ****************
> vdW correction (ff) Stress -0.00517761
> -0.00000010
> Local Pseudopotential/Core Stress -0.88167272
> -0.56052030
> Nonlocal Pseudopotential Stress 2.92262879
> 20.96427765
> Exact Exchange Stress -0.00000000
> -0.00000000
> Sum of Parts Stress -1732.75667328
> ****************
> Total Stress 0.00785295
> -0.00000014
>
> ==============================================================================
> STRESS TENSOR [GPa]
> X Y Z
> X -0.05130320 0.02112443 -0.15716038
> Y 0.02112443 0.07439468 -0.03381687
> Z -0.15716038 -0.03381687 0.04697689
> 1/3 Trace(stress tensor): 2.33561233E-02
> Det(stress tensor) : -1.75455374E-03
>
>
>
> while in pressure file I got following output
>
>
>
> # Step Time [fs] xx [bar] xy [bar] xz
> [bar] yx [bar] yy [bar] yz [bar]
> zx [bar] zy [bar] zz [bar]
> 0 0.000 2291.7724124002 -7.8261381151
> -11.6256055821 -7.8261381151 2225.2853884787 190.2135354318
> -11.6256055821 190.2135354318 2617.3106021379
> 1 0.500 1721.2682620818 206.1262199908
> -1539.1469767016 206.1262199908 2804.1547381410
> -143.2394364947 -1539.1469767016 -143.2394364947 2958.6420055205
>
>
>
> Both files have values different units (GPa in stress file and bar in
> pressure file). After converting values to same unit (say bar) the xx
> stress value 10.60 bar (0.00106044 GPa) does not match with the value of
> 2291.77 bar in the pressure file. Can you please help me to understand this
> ? Am I doing something wrong in my input file. The print output of cell
> vectors from the MOTION section is following:
>
>
>
> # Step Time [fs] Ax [Angstrom] Ay [Angstrom] Az
> [Angstrom] Bx [Angstrom] By [Angstrom] Bz [Angstrom]
> Cx [Angstrom] Cy [Angstrom] Cz [Angstrom] Volume
> [Angstrom^3]
> 0 0.000 16.9813194275 0.0000000000
> 0.0000000000 0.0009342941 17.1132431030 0.0000000000
> -0.0392083935 0.0056124185 17.0369434357
> 4951.0285723949
> 1 0.500 16.9878393880 -0.0026240361
> 0.0088682212 -0.0017097687 17.1090517191 0.0016270059
> -0.0303270449 0.0072363688 17.0367331490
> 4951.6596469487
>
>
>
> Many thanks ,
>
> Abhishek
>
>
>
>
>
>
>
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