# canorb energies in mcscf

Falcetta_Michael Falcetta_Michael at roberts.edu
Tue Sep 11 14:30:20 BST 2001

```Dear Molpro Users:

I am doing an mcscf, extracting several states of a cation system
(equally weighted) and trying to understand the canonical orbital
energies I am getting.  In the symmetry block under consideration, there
are 2 core and 7 valence orbitals and thus the first 9 orbitals in the
symmetry block are accounted for.  If I include only 9 orbitals in the
active space for this symmetry block, and print the canorbs the energy
of the 10th (i.e. first nonactive orbital) is about -.07 au and the
energy of the 9th orbital is positive.  I then start with these
canonical orbitals and allow 11 orbitals in the active space for this
the symmetry block and now the 12th orbital has an energy of about -.07
and the energies of the 10th and 11th orbitals are positive.  Finally I
have expanded the active space to include 15 orbitals in this symmetry
and the Occ numbers and energies are given below.  I have also tried to
rotate orbitals 14 and 16 to ensure that the initial guess includes the
orbital I want in the active space.  You'll note that the energies of
some of my active orbitals are above 1 hartree.  My question is: are
these energies correct? and if so, does that mean that I am getting very
high energy orbitals into the active space?  Then how do I get the
calculation use the much lower energy external orbitals (for example
orbs 16 and 17 below)?

Mike Falcetta

Orb     Occ        Energy

1.1  2.00000   -21.113878

2.1  2.00000   -11.741709

3.1  1.97590    -1.896946

4.1  1.72258    -1.102576

5.1  1.91319    -0.973930

6.1  1.53756    -0.906814

7.1  1.33268    -0.737594

8.1  0.49390    -0.265931

9.1  0.01706     0.401921

10.1  0.02853     0.743152

11.1  0.01646     0.899204

12.1  0.00779     1.153367

13.1  0.00348     1.252850

14.1  0.00298     1.606205

15.1  0.00194     1.685566

16.1  0.00000    -0.071171

17.1  0.00000    -0.070372

18.1  0.00000    -0.061979

19.1  0.00000    -0.040635

20.1  0.00000    -0.039509

21.1  0.00000    -0.036030

22.1  0.00000    -0.025585

23.1  0.00000    -0.017070
Dr. Mike Falcetta

Associate Professor of Chemistry
Roberts Wesleyan College
2301 Westside Drive
Rochester, NY 14624

```