*ESR

This section gives directives for the calculation of ESR/EPR parameters, g-tensors and Hyperfine Coupling tensors (HFC).

General control statements

.PRINT

Print level.

Default:

.PRINT
 0

Definition of the multiplicity and CI

.MULTIP

.MULTIP
 2

Default: Doublet for an odd number of electrons, triplet for an even number of electrons.

.CI ROOTS

.CI ROOTS
 5

Default: The multiplicity.

.ESR CI

Genreal specification of the ESR CI space with GAS, generalized active spaces. For easier description they are divided in three groups: RAS1-GAS spaces, defining max number of holes in the doubly occupied orbitals in the reference wave function; RAS2-GAS, one “CAS” space with the open shells from the reference wave functions; RAS3-GAS spaces, defining max number of electrons in the empty (virtual) orbitals in the refenece wave function.

Default: “RESOLVE”, that is, CI in the open shell orbitals from the reference wave function.

Example: S, SD, and SDT from the occupied orbitals, S and SD to the empty orbitals. The RAS2-GAS space is defined implicitly by the reference wave function, typically and average-of-configurations (AOC) Hartree-Fock. The example is for a case with inversion symmetry, if no inversion symmetry there is only one set orbitals in each GAS space.

.ESR CI
2        ! 3 RAS1-GAS spaces and 2 RAS3-GAS spaces
        ! max 1 hole in first RAS1-GAS space
2        ! 2 g and 2 u orbitals in RAS1-GAS
        ! max 2 holes in second RAS1-GAS space
2        ! 4 g and 2 u orbitals in RAS1-GAS
        ! max 3 holes in third and last RAS1-GAS space
1        ! 4 g and 1 u orbitals in RAS1-GAS
        ! max 2 electrons in first RAS3-GAS space
1        ! 4 g and 1 u orbitals in RAS3-GAS
        ! max 1 electron in second and last RAS3-GAS space
1        ! 4 g and 1 u orbitals in RAS3-GAS

.THRCI

.THRCI
 1.d-5

Default: 1.d-4 for ppt accuracy. Can also be modified with .G10PPM keyword.

.G10PPM

Converge CI for 10 ppm accuracy in g-tensor values, default is ppt accuracy.

.STATE

The first CI root belonging to the multiplet of quasi-degenerate states. For example, if the ground state is a non-degenerate singlet state (non-relativistically a spin singlet) followed by the triplet state you want to study, then you should specify state no. 2 here.

Default:

.STATE
 1

.KR-CON

Use Kramers conjugation for odd-number of electrons. For a doublet state this means the program only needs to converge one CI state instead of two CI states - reduces the CI time with a factor 2.

Definition of additional properties

The g-tensor and HFC-tensors for all selectred nuclei are always calculated.

.SELECT

Select which nuclei to calculate HFC for. Default is all, which can be quite time-consumig if the molecule has many atoms. (You cannot use .SELECT under **INTEGRALS if you use this keyword, they do the same thing. It is included here for convenience.) To select three nuclei, no. 3, 7, and 8:

.SELECT
 3
 3 7 8