MOLPRO also allows the writing of simple input programs, which check for conditions or perform loops over certain parts of the input. IF blocks and DO loops have a similar form as in Fortran.
One line IF:
IF (condition) command
If more than one command depends on the condition, IF blocks can be used:
IF (condition) THEN commands END IF
or
IF (condition) THEN commands ELSE commands END IF
Also the structure of DO loops is as in Fortran:
DO ivar=istart,iend,[increment] commands ENDDO
ivar is the loop index variable, istart, iend, increment are either numbers or variables. The default for increment is 1.
Examples:
Loop over several geometries (potential curve for HCl):
***,HCl geometry= !Z-matrix geometry input h cl,h,r
r=1.5 !start value for bond distance hf !Hartree-Fock for start geometry
do i=1,10 !loop over bond distances
casscf; !perform casscf ecas(i)=energy !save casscf energy in array ecas mrci !perform mrci rhcl(i)=r !save distances in array rhcl emrci(i)=energy !save mrci energies in array emrci emrda(i)=energd !save Davidson corrected energies in array emrda
r=r+0.2 !increment r end do
Alternatively, one could predefine a number of distances:
***,HCl
rhcl=[1.6,1.8,2.0,2.2,2.3,2.4,2.5,2.7,3.0,3.5,4.0,5.0,6.0,7.0]
geometry= !Z-matrix geometry input h cl,h,r
do i=1,#rhcl !loop over all distances r=rhcl(i) !set r to current bond distance
if(i.eq.1) then !in first calculation, do Hartree-Fock hf !Hartree-Fock for start geometry end if
casscf; !perform casscf ecas(i)=energy !save casscf energy in array ecas mrci !perform mrci rhcl(i)=r !save distances in array rhcl emrci(i)=energy !save mrci energies in array emrci emrda(i)=energd !save Davidson corrected energies in array emrda end do
One can skip to some command later in the input using GOTO. For instance
if(orbital.ne.0) goto casscf !skip to casscf if an orbital record exists hf !Hartree-Fock casscf; !casscf
molpro@molpro.net 2010-07-28