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

[yannickf]

Dear Joan,


you can only use X2C with PCC and the derivatives of the unitary decoupling in the release version. So, you always get the full analytical derivative. DKH and BSS are not implemented as these are outdated theories and I did not want to implement it. You can simply use "$pnmr hfc-only" and get the results for the total HFC, the paramagnetic spin-orbit term, and the sum of the Fermi-contact and the spin-dipole term. Decoupling the Fermi-contact and the spin-dipole term is only possible in the non-relativistic limit (you can delete $rx2c before an mpshift run and use the non-relativistic EPR operators with the X2C-optimized density, i.e. without PCC). Below is a modified control:

Code: [Select]

$title
Cu(SMe)4 B3LYP ANO-DK3 Uncontracted HFC Term Decomposition Test 1
$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
$rx2c
$finnuc
$snso
$snsopara 0
$dft
    functional   b3-lyp
    gridsize   5a
$scfconv   9
$scforbitalshift  closedshell=.05
$ricore      500
$rij
$jbas    file=auxbasis
$pnmr hfc-only
$rundimensions
   natoms=21
$last step     mpshift

PCC is always activated for NMR, EPR, and pNMR properties as results without PCC are typically wrong by orders of magnitude. With this settings you will get the following output for every nucleus.
1) Scalar-relativistic part, i.e. the Fermi-contact plus spin-dipole interaction (molecular frame)
2) The paramagnetic spin-orbit part (molecular frame)
3) Total HFC tensor in principal axis system
4) Eigenvectors for the principal axis system

Version 7.8 prints some more results and the Euler transformations.

Hope this helps.

Best wishes,

Yannick