Example: Phase Transition Due To External Nonuniform Stress
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"Download Diamond_from_pressure.run"

   #!/bin/sh

   # Starting from hexagonal graphite we optimize the crystal
   # under the influence of a non-uniform stress tensor.
   # The system will undergo a phase transition to a diamond structure
   AMS_JOBNAME=Graphite2Diamond $AMSBIN/ams << eor

   Task GeometryOptimization
   EngineAddons
       ExternalStress
           StressTensorVoigt 0 0 0.01 0 -0.0003 0
       End
   End
   System
       Atoms
           C  0.0000   0.0000   1.6507
           C  0.0000   0.0000  -1.6507
           C  0.0000  -1.4225   1.6507
           C  0.0000   1.4225  -1.6507
       End
       Lattice
           1.2319  -2.1338   0.0000
           1.2319   2.1338   0.0000
           0.0000   0.0000   6.6029
       End
   End
   GeometryOptimization
       MaxIterations 300
       OptimizeLattice Yes
       Convergence
           Energy 1.0e-6
           Gradients 1.0e-5
           Step 1.0e-4
       End
   End
   UseSymmetry No
   Engine DFTB
       Model SCC-DFTB
       ResourcesDir DFTB.org/3ob-3-1
       DispersionCorrection D3-BJ
       KSpace
           Quality Basic
       End
   EndEngine

   eor

   # The diamond structure is still compressed under the influence of the external stress.
   # We now disable this term and relax the unit cell with the same DFTB model
   AMS_JOBNAME=DiamondRelaxation $AMSBIN/ams << eor

   Task GeometryOptimization
   LoadSystem 
       File Graphite2Diamond.results/ams.rkf
   End
   GeometryOptimization
       MaxIterations 300
       OptimizeLattice Yes
       Convergence
           Energy 1.0e-6
           Gradients 1.0e-5
           Step 1.0e-4
       End
   End
   UseSymmetry No
   LoadEngine Graphite2Diamond.results/dftb.rkf

   eor
