isotops in properties

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Marcin Gronowski

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Apr 2, 2021, 11:50:23 AMApr 2
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Dear Dirac experts,

I will perform series of computations of nuclear spin-rotation constant, spin-spin coupling, and nuclear quadrupole coupling constants. I wonder if I can specify the isotopic composition of my molecule. In a perfect situation, it will be good to have results for all isotopes in one output. I have run a test job. It seems that Nuclear quadrupole coupling constants are printed for all isotopes (this is great). Unfortunately, nuclear spin-rotation tensor is printed only for the most abundant isotope, despite the list of isotopes contains more than one position. Below, you can found the most relevant parts of the output (Na2K2 stoichiometry).

All the best,
Marcin


$ grep -A 37 'Contents of the input file' my_out.out
Contents of the input file
--------------------------
**DIRAC
.TITLE
qcorr
.WAVE FUNCTION
.PROPERTIES
**INTEGRALS
.NUCMOD
2
**HAMILTONIAN
.DOSSSS
.INTFLG
1 1 1
**WAVE FUNCTION
.SCF
*SCF
.MAXITR
222
.EVCCNV
7.0D-9
**MOLTRA
.ACTIVE
energy -999.9 999.0 10.0
**PROPERTIES
.SPIN-ROTATION
.NQCC
.PRINT
4
**MOLECULE
*CHARGE
.CHARGE
0
*BASIS
.DEFAULT
dyall.v2z
**END OF

$ grep @ my_out.out
 *                   @@@@@    @@   @@@@@     @@@@     @@@@@                    *
 *                   @@  @@        @@  @@   @@  @@   @@                        *
 *                   @@  @@   @@   @@@@@    @@@@@@   @@                        *
 *                   @@  @@   @@   @@ @@    @@  @@   @@                        *
 *                   @@@@@    @@   @@  @@   @@  @@    @@@@@                    *
@ Nuclear species:
@ name  charge  isotope   mass         abundance     g factor
@ Na        11        1    23.000000     100.000     1.478437
@ K         19        1    39.000000      93.258     0.261005
@                     2    41.000000       6.730     0.143262

$ grep -A 3 ' Spin-rotation constants' v2z.dal_Na2K2.out
                     Spin-rotation constants (kHz) for Na   1
                     ----------------------------------------
  Nuclear g-value:     1.478437
--
                   Spin-rotation constants (in ppm) for Na   1
                   -------------------------------------------
--
                     Spin-rotation constants (kHz) for Na   2
                     ----------------------------------------
  Nuclear g-value:     1.478437
--
                   Spin-rotation constants (in ppm) for Na   2
                   -------------------------------------------
--
                     Spin-rotation constants (kHz) for K    1
                     ----------------------------------------
  Nuclear g-value:     0.261005
--
                   Spin-rotation constants (in ppm) for K    1
                   -------------------------------------------
--
                     Spin-rotation constants (kHz) for K    2
                     ----------------------------------------
  Nuclear g-value:     0.261005
--
                   Spin-rotation constants (in ppm) for K    2
                   -------------------------------------------

Agustín

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Apr 6, 2021, 7:56:48 AMApr 6
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Dear Marcin,

To calculate nuclear spin-rotation tensors you can select the isotopic composition you want to use in a given molecular systems by writing "Isotope=..." on the *.mol file. You are welcome to see an example on this Tutorial: http://www.diracprogram.org/doc/release-19/tutorials/spinrot/tutorial.html .

Unfortunately, DIRAC cannot print values of nuclear spin-rotation constants for all the different isotopes of each nucleus at your molecule (as it can for spin-spin couplings, NQCC and other properties). This is because for spin-rotations there is a dependence on the isotopes for the calculation of the linear response function (the total electronic orbital angular momentum operator depends on the center of mass). In addition, also the inertia tensor is calculated with respect to the CM, and so it also depends on the chosen isotopes.

I will be attentive in case these comments are not clear enough.

Best regards,
Agustín
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