SCM: Examples BAND

Calculating the atomic forces

Sample directory: band/BNForce/

This example shows how to calculate the gradient of the energy with respect to atomic displacements, using the GRADIENTS key block.

$ADFBIN/band << eor
Title BN zincblende structure (force calculation)

comment 
  Calculate Atomic Forces (energy gradient)
  Frozen core approximation
  TZ2P basis
  A/K -> 5/3
  2 atoms per unit cell
end 

dependency basis=1e-8

Kspace 3 
Accuracy 5.0 

Units 
  Length Angstrom 
End 

Define 
   a = 3.60
End 

GRADIENTS 
END

Lattice  
  0.0   0.5*a 0.5*a 
  0.5*a 0.0   0.5*a 
  0.5*a 0.5*a 0.0  
End 

Atoms B  
  0.0 0.0 0.0 
end 

Atoms N 
  0.2404*a 0.2404*a 0.2404*a 
end 

BasisDefaults
BasisType TZ2P
Core Large
End

END INPUT
eor

In the output you will find the result

 FINAL GRADIENTS
    1  B  0.019676  0.019676  0.019676
    2  N -0.019677 -0.019677 -0.019677

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