Example: External electric field¶

#! /bin/sh

# Induce a dipole moment in benzene by applying a field orthogonal to the ring

for EField in 0 0.051422 0.51422 5.1422 ; do # which is 0.001 0.01 0.1 in atomic units

AMS_JOBNAME=benzene_$EField $AMSBIN/ams << eor

Task SinglePoint
System
    Atoms
        C  2.09820318  1.21139817   0.0
        C -0.69940106  1.21139817   0.0
        C  1.39880212  0.0          0.0
        C  1.39880212  2.42279634   0.0
        C  0.0         2.42279634   0.0
        C  0.0         0.0          0.0
        H  3.18949204  1.21139817   0.0
        H  1.94444655  3.36788021   0.0
        H -0.54564443  3.36788021   0.0
        H -1.79068992  1.21139817   0.0
        H -0.54564443 -0.94508387   0.0
        H  1.94444655 -0.94508387   0.0
    End
    ElectrostaticEmbedding
        ElectricField 0.0 0.0 $EField
    End
End

Engine MOPAC
EndEngine

eor

done

# If I apply an electric field of 1 [a.u.] (51.42 Volt/Angstrom = 1 a.u.) on a system with charge 1,
# I expect the net force to be equal to the 1 [a.u.]

AMS_JOBNAME=OH_plus $AMSBIN/ams << eor

Task SinglePoint
System
    Atoms
        O 0.0 0.0 0.0
        H 1.0 0.0 0.0
    End
    Charge 1
    ElectrostaticEmbedding
        ElectricField 0.0 51.422 0.0
    End
End

Properties
    Gradients Yes
End

Engine MOPAC
EndEngine

eor