Example: Analytical stress tensor Urea¶

#!/bin/sh
$AMSBIN/ams << eor

Task GeometryOptimization 
System
    Atoms
          C      -0.353812500     2.476687500     1.569096000
          C       2.476687500    -0.353812500    -1.569096000
          O      -0.353812500     2.476687500    -1.899878400
          O       2.476687500    -0.353812500     1.899878400
          N       0.460805400    -2.369694600     0.863238400
          N      -1.168430400     1.662069600     0.863238400
          N      -2.369694600    -1.168430400    -0.863238400
          N       1.662069600     0.460805400    -0.863238400
          H       1.073891700    -1.756608300     1.337736800
          H      -1.781516700     1.048983300     1.337736800
          H      -1.756608300    -1.781516700    -1.337736800
          H       1.048983300     1.073891700    -1.337736800
          H       0.418914000    -2.411586000    -0.130051200
          H      -1.126539000     1.703961000    -0.130051200
          H      -2.411586000    -1.126539000     0.130051200
          H       1.703961000     0.418914000     0.130051200
    End
    Lattice
          5.661000000     0.000000000     0.000000000
          0.000000000     5.661000000     0.000000000
          0.000000000     0.000000000     4.712000000
    End
End

NumericalDifferentiation
  StrainStepSize 0.00001
  Parallel nCoresPerGroup=1
End

GeometryOptimization 
  OptimizeLattice yes
  Convergence Gradients=1e-3
  Method Fire
End


Engine DFTB
    Model DFTB3
    ResourcesDir DFTB.org/3ob-3-1
    DispersionCorrection D3-BJ
    Technical
      EwaldSummation Enabled=yes
      AnalyticalStressTensor yes
    End
    KSpace Quality=GammaOnly
EndEngine

eor