# [molpro-user] calculating dipole moment using finite field

Mahdi Yousefi Atashgah myous005 at odu.edu
Sat Mar 31 17:53:37 CEST 2018

```Hi,
I'm trying to calculate AlCl dipole moment at equilibrium using finite
field by below input:

***,AlCl finite field calculations
ANGSTROM
r=[2.130143]                !set geometry parameters
geometry={Al;Cl,Al,r}
basis=aug-cc-pv6z                        !define default basis
field=[0,0.0003,-0.0003]             !define finite field strengths
\$method=[hf,casscf,ccsd,ccsd(t)]

k=0
do i=1,#field                      !loop over fields
dip,,,field(i)                   !add finite field to H
do m=1,#method                   !loop over methods
k=k+1
\$method(m)                     !calculate energy
!expec,dm   !calculate dipole moments for ACPF
e(k)=energy                    !save energy
enddo
enddo
k=0
n=#method
do m=1,#method
k=k+1
energ(m)=e(k)
dipmz(m)=(e(k+n)-e(k+2*n))/(field(2)-field(3))   !dipole moment as
first energy derivative

dpolz(m)=(e(k+n)+e(k+2*n)-2*e(k))/((field(2)-field(1))*(field(3)-field(1)))
!polarizability as second der.
enddo

table,method,energ,dipmz,dpolz
title,results for AlCl, r=\$R

however, the output gives me below error:
SETTING E(6)           =      -701.56161745  HARTREE

SETTING K              =         0.00000000

SETTING N              =         2.00000000

DO M                   =         1.00000000
SETTING K              =         1.00000000

SETTING ENERG(1)       =      -701.51812000  HARTREE

SETTING DIPMZ(1)       =        -0.57529364  HARTREE

? Error