8.1 SUBROUTINE READ_OP

c----------------------------------------------------------------------
      subroutine read_op(oper,opnuc,name,icomp,isy,np,origin,isyop1)
c----------------------------------------------------------------------
      implicit double precision (a-h,o-z)
      character*(*) name
      dimension oper(*),origin(3)

reads one-electron operator name or make it if unavailable.

oper must be dimensioned ntqg (np=0) or ntdg (np=1).

Input parameters:

name

name of operator (string)

icomp

component number.
icomp$>0$, name must be a generic operator name.
icomp$=0$, name must refer to a component.

np

np=0: return operator as square matrix in oper;
np=1: return operator as lower triangle in oper.

isy

if nonzero, matrix of this symmetry is read.
If zero, first nonzero matrix is read.
Note: if the origin of the operator is not at (0,0,0), then several symmetries may give contributions.

origin

Optional specification of the operator origin.
If the operator name has no extension, the origin will be (0,0,0).
If the operator name is of the form name(center), the operator origin will be at the given center (z-matrix row number or symbol).
If the operator name is of the form name(0), the operator will be evaluated at the given origin. In this case origin must hold the $x$, $y$, $z$ values of the origin (in au).

Output parameters:

oper

operator in AO basis

opnuc

nuclear value of operator

isyop1

symmetry of operator. If the operator for the requested symmetry is zero, isyop1=0 is returned