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## 4.4 Variables

MOLPRO stores all important results in variables. For example, the Hartree-Fock program sets the variables ENERGY, DMX, DMY, DMZ, holding the final energy and dipole moments. These variables can be used for further analysis. For a list of variables set by other programs see section 19.3. Variables can be used in expressions, quite similar to fortran.

For example, it is possible to compute a reaction energy in one job. Let's take CO + H HCO as a simple example.

***,example for reaction energy

basis=avtz               !basis set (used for all molecules)

geometry={c;o,c,2.13}    !geometry for CO
hf                       !do Hartree-Fock calculation
ccsd(t)                  !ccsd(t) calculation
e_co=energy              !save energy for the CO molecule

geometry={h1;h2,H1,1.4}  !geometry for H2
hf                       !do Hartree-Fock calculation
ccsd(t)                  !ccsd(t) calculation
e_h2=energy              !save energy for the CO molecule

geometry={               !geometry for H2CO
C
O  , C , rco
H1 , C , rch , O , hco
H2 , C , rch , O , hco , H1 , 180
}

rco=1.182 Ang
rch=1.102 Ang
hco=122.1789 Degree
hf                       !do Hartree-Fock calculation
ccsd(t)                  !ccsd(t) calculation
e_h2co=energy            !save energy for H2CO

de=(e_h2co-e_h2-e_co)*tokJ   !reaction energy in Kilojoule.


molpro@molpro.net 2018-03-18