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. For more details on consult the documentation for Gradients.

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

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