[DFTB-Plus-User] What do the Pressure indicate?

[jsxz]

Dear all,
I am running the SCC-DFTB with the VelocityVerlet method,Driver = VelocityVerlet {  MovedAtoms = 1:-1  Steps = 10000
  KeepStationary = Yes
  TimeStep [fs] = 1.0
  MDRestartFrequency = 1
  OutputPrefix = "geom.out"
  Thermostat = None {}
  Velocities [AA/ps] = {                
   <<< "velocity.txt"
   }
   ConvergentForcesOnly = No 
}

I find the pressure in md.out different from that in out.log, Which are as follows: 


In the file: md.out
 MD step:           0
 Pressure:                          -0.311743E-05 au    -0.917179E+08 Pa
 Potential Energy:                -494.7211745146 H       -13462.0481 eV
 MD Kinetic Energy:                  9.5186349932 H          259.0152 eV
 Total MD Energy:                 -485.2025395214 H       -13203.0329 eV
 MD Temperature:                     0.0221106504 au        6981.9828 K
...
...
 MD step:       10000
 Pressure:                          -0.339071E-05 au    -0.997580E+08 Pa
 Potential Energy:                -490.2082249886 H       -13339.2445 eV
 MD Kinetic Energy:                  4.9888127115 H          135.7525 eV
 Total MD Energy:                 -485.2194122771 H       -13203.4920 eV
 MD Temperature:                     0.0115884151 au        3659.3277 K
In the file:  out.log
********************************************************************************
** Geometry step: 0
********************************************************************************
MAXNEIGHBORS: 2561
  iSCC Total electronic   Diff electronic      SCC error    
    1   -0.51582486E+03    0.00000000E+00    0.11868403E-04
    2   -0.51582486E+03   -0.10265921E-09    0.78293993E-05
scc total               CPU:     7.38       Wall:     7.42
 Total Energy:                    -494.7011653169 H
 Total Mermin free energy:        -494.7211745146 H
force total             CPU:     0.99       Wall:     1.01
 Volume:                             0.172487E+07 au^3
 Pressure:                           0.561541E-06 au     0.165211E+08 Pa
>> Charges saved for restart in charges.bin
 MD Temperature::                    0.0221106504 H         6981.9828 K
 MD Kinetic Energy:                  9.5186349932 H
 Total MD Energy:                 -485.2025395214 H

...
...
********************************************************************************
** Geometry step: 10000
********************************************************************************
MAXNEIGHBORS: 2561
  iSCC Total electronic   Diff electronic      SCC error    
    1   -0.51191555E+03    0.00000000E+00    0.14908229E+00
    2   -0.51173238E+03    0.18317087E+00    0.40312730E+00
    3   -0.51193732E+03   -0.20493450E+00    0.67927614E-01
    4   -0.51193530E+03    0.20158403E-02    0.96219530E-01
    5   -0.51194305E+03   -0.77460598E-02    0.14910683E-01
    6   -0.51194297E+03    0.77176499E-04    0.72112883E-02
    7   -0.51194288E+03    0.92423888E-04    0.22124927E-01
    8   -0.51194311E+03   -0.23527271E-03    0.57641324E-02
    9   -0.51194310E+03    0.79870361E-05    0.34686526E-02
   10   -0.51194310E+03    0.80522580E-06    0.12716026E-02
   11   -0.51194314E+03   -0.37330772E-04    0.44577841E-03
   12   -0.51194314E+03    0.33205728E-05    0.23560681E-03
   13   -0.51194314E+03    0.16375881E-05    0.80152822E-04
   14   -0.51194314E+03   -0.24583005E-06    0.51844159E-04
   15   -0.51194313E+03    0.45254882E-06    0.64249756E-05
scc total               CPU:    54.94       Wall:    54.97
 
 Total Energy:                    -490.1918593225 H
 Total Mermin free energy:        -490.2082249886 H
force total             CPU:     0.81       Wall:     0.80
 Volume:                             0.172487E+07 au^3
 Pressure:                          -0.146252E-05 au    -0.430288E+08 Pa
>> Charges saved for restart in charges.bin
 MD Temperature::                    0.0115884151 H         3659.3277 K
 MD Kinetic Energy:                  4.9888127115 H
 Total MD Energy:                 -485.2194122771 H
 
Molecular dynamics completed
MD information accumulated in md.out
program total           CPU: ********       Wall: ********


 What do the pressures in the two files  indicate, respectively?


Thanks!
xiaobao
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.zfn.uni-bremen.de/pipermail/dftb-plus-user/attachments/20160121/f1ea1ae6/attachment.htm>