Example: Calculating the atomic forces

Download BNForce.run

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)

DefaultsConvention 2014

Gradients
End

NumericalQuality Basic  ! for speed, not very accurate

Units
   Length Angstrom
End

Define
   a = 3.60
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  0.000000 0.000000 0.000000
   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  0.017517  0.017517  0.017517
   2  N -0.017517 -0.017517 -0.017517