Hyperfine Coupling Interaction Decomposition

[jcardol]

Dear Turbomole Users,

I was wondering if there is an option to break down the Hyperfine Coupling into its different interaction components, mainly FC (Fermi Contact) Interaction and SD (Spin-Dipole) Interaction, so that it is printed in the output file.

Any help would be greatly appreciated. 

Best Regards!

                      - Joan

[yannickf]

Dear Joan,

this is a very late reply. But I would stil like to answer your questions. In the two-component implementation in ridft (DOI: 10.1021/acs.jctc.1c01027), we can only partition the tensor into the scalar-relativistic contribution and the spin-orbit part. The latter corresponds to the paramagnetic spin-orbit term, which can also be calculated via perturbation theory in mpshift (DOI: 10.1021/acs.jpca.2c03579) in a non-relativistic framework or the X2C framework. The scalar-relativistic part describes both the FC and the SD term. Unfortunately, these are coupled in X2C, see DOI: 10.1021/acs.jpca.1c07793. The FC term is mainly the result on the diagonal of the scalar-relativistic tensor. However, the FC+SD can only be fully decoupled in the non-relativistic limit. Then, you can separate them by integration by parts after summing the Dirac small-large and large-small part.

If you have access to V7.7, you can also use mpshift for the EPR properties. I have ported all EPR capabilities to this module and added some features for user-friendliness.

Best and happy holidays,

Yannick

[jcardol]

Dear Yannick,

thank you so much for your reply and pointing out all the related literature, it was really helpful! I was wondering, then, how to obtain the hyperfine coupling Fermi Contact, Spin Dipole Contribution and Spin-Orbit coupling terms individually from a mpshift calculation. I am currently using as input:

Code: [Select]

$title
$symmetry c1
$coord    file=coord
$optimize
 internal   off
 redundant  off
 cartesian  on
$atoms
    basis =ANO-DK3
    jbas  =universal
$basis    file=basis
$uhfmo_alpha   file=alpha
$uhfmo_beta   file=beta
$uhf
$alpha shells
 a       1-66                                   ( 1 )
$beta shells
 a       1-65                                   ( 1 )
$scfiterlimit      300
$scfdamp   start=1.000  step=0.050  min=0.100
$scfdump
$scfdiis
$maxcor    500 MiB  per_core
$energy    file=energy
$grad    file=gradient
$pop
$rdkh 4
$finnuc
$snso
$snsopara 0
$pcc
$dft
    functional   b3-lyp
    gridsize   5a
$scfconv   9
$scforbitalshift  closedshell=.05
$ricore      500
$rij
$jbas    file=auxbasis
$pnmr fc sd psoso temp=  298.00
$rundimensions
   natoms=21
$last step     mpshift


Before launching the mpshift calculation, I use the ridft module to calculate an energy. I have been testing with DKH, but it outputs too big of a HFC constants, I've tried with and without PCC and changing SNSO but it remains too high. Instead when usign X2C one-component calculation it gives reasonable values although I am not capable of finding the paramagnetic output of the Hyperfine Tensor decomposition, just the PSOSO in all calculations.

Thanks for your time and patience and best regards!

Joan