[DFTB-Plus-User] The value of pressure after geometry optimization

[Mat Toliday]

Moyassar,
In the Driver section you need to set the following values "LatticeOpt = Yes", and "FixLengths = " followed by the appropriate three values. These values will depend on wheather you are using 1, 2 or 3d boundary conditions and if not using 3d then the orientation of your 1d or 2d structure. If you do this you will see "LatticeStep = "  in the output at the start of each step and after "Maximal force component:" you should see another line reading "Maximal Lattice component:" 
All the best,
Mat Tolladay





On Saturday, 28 March 2020, 22:07:57 CET, Moyassar Meshhal via DFTB-Plus-User <dftb-plus-user at mailman.zfn.uni-bremen.de> wrote: 





  




Dear dftb+ users,




Below is the last part of the output file of a geometry optimization job for a periodic system (namely, graphene oxide).

Although the geometry is converged, I noticed that the value of the pressure is quite high (0.565001E+10)!

Is this normal? or what I missed?

BTW, I didn't set any value for the external pressure in the input file, so the default value is used (which I guess to be 0.0, isn't it?).

I would appreciate an explanation, as well as any recommendation that might improve my calculations.




Best Regards,

Moyassar




-----------------

 iSCC Total electronic   Diff electronic      SCC error

    1   -0.18929725E+03    0.00000000E+00    0.27230171E-03

    2   -0.18929725E+03   -0.60135307E-07    0.11783150E-03

    3   -0.18929725E+03   -0.63194534E-08    0.56211281E-04

    4   -0.18929725E+03   -0.25149518E-08    0.29964703E-04

    5   -0.18929725E+03   -0.22265567E-09    0.65231892E-05




Total Energy:                     -186.0771157290 H        -5063.4159 eV

Extrapolated to 0:                -186.0771157324 H        -5063.4159 eV

Total Mermin free energy:         -186.0771157358 H        -5063.4159 eV

Force related energy:             -186.0771157358 H        -5063.4159 eV

Volume:                              0.849771E+04 au^3   0.125923E+04 A^3

Pressure:                            0.192040E-03 au     0.565001E+10 Pa

Maximal force component:             0.731554E-04

>> Charges saved for restart in charges.bin




Geometry converged




--------------------------------------------------------------------------------

DFTB+ running times                          cpu [s]             wall clock [s]

--------------------------------------------------------------------------------

Pre-SCC initialisation                 +   249.76  ( 11.9%)    140.69  (  9.7%)

SCC                                    +  1297.50  ( 61.9%)   1134.72  ( 78.3%)

Post-SCC processing                    +   549.67  ( 26.2%)    174.55  ( 12.0%)

--------------------------------------------------------------------------------

Missing                                +     0.15  (  0.0%)      0.01  (  0.0%)

Total                                  =  2097.08  (100.0%)   1449.98  (100.0%)

--------------------------------------------------------------------------------





























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