NQCC in nonlinear molecule

[Marcin Gronowski]

Dear Dirac Experts,

I'm trying to compute NQCC for the sets of nonlinear molecules. I selected H2S as test molecules. The experimental values are (approximately): Xaa=-32 MHz, Xbb=-8 MHz, Xcc=40 MHz (page 417 in " MICROWAVE MOLECULAR SPECTRA" by Gordy  & Cook, Wiley, 1984). The values predicted at SCF/ae3z level are completely different Xxx=2.22 MHz, Xyy=-3.84 MHz, Xzz=-1.61 MHz. What's more, the EFG components multiplied by 234.9647 and quadrupole moment of 33S (-0.0678 Barn) are very close to the experimental values (the order of axis is different). I do not understand the situation. I guess that Dirac's NQCC values may base on another definition of the quadruple nuclear coupling constant. I will be very grateful for any help.

All the best
Marcin

[Marcin Gronowski]

I forgot to add the output. Bellow, you can found the most important parts of the output:

Configuration and build information
-----------------------------------

Who compiled             | root
Compiled on server       | n01.cluster.local
Operating system         | Linux-3.10.0-514.6.1.el7.x86_64
CMake version            | 3.14.7
CMake generator          | Unix Makefiles
CMake build type         | release
Configuration time       | 2020-04-16 06:45:55.979783
Python version           | 2.7.5
Fortran compiler         | /usr/bin/gfortran
Fortran compiler version | 4.8.5
Fortran compiler flags   |  -g -fcray-pointer -fbacktrace -fno-range-check -DVAR_GFORTRAN -DVAR_MFDS
C compiler               | /usr/bin/gcc
C compiler version       | 4.8.5
C compiler flags         |  -g
C++ compiler             | /usr/bin/g++
C++ compiler version     | 4.8.5
C++ compiler flags       |  -g -Wall -Wno-unknown-pragmas -Wno-sign-compare -Woverloaded-virtual -Wwrite-strings -Wno-unused
Static linking           | False
64-bit integers          | False
MPI parallelization      | False
MPI launcher             | unknown
Math libraries           | /lib64/liblapack.so;/lib64/libblas.so
Builtin BLAS library     | OFF
Builtin LAPACK library   | OFF
Explicit libraries       | unknown
Compile definitions      | HAVE_SYSTEM_NATIVE_BLAS;HAVE_SYSTEM_NATIVE_LAPACK;SYS_LINUX;PRG_DIRAC;INSTALL_WRKMEM=64000000;HAS_PCMSOLVER;BUILD_GEN1INT;HAS_PELIB;MOD_QCORR;HAS_STIELTJES


 LAPACK integer*4/8 selftest passed
 Selftest of ISO_C_BINDING Fortran - C/C++ interoperability PASSED

Execution time and host
-----------------------


     Date and time (Linux)  : Mon May 10 08:42:51 2021
     Host name              : n02


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
9.0D-9
**MOLTRA
.ACTIVE
energy -999.9 999.0 10.0
**PROPERTIES
.EFG
.NQCC
.PRINT
4
**MOLECULE
*CHARGE
.CHARGE
0
*BASIS
.DEFAULT
dyall.ae3z
**END OF


Contents of the molecule file
-----------------------------

3
H2S geom jakies
H 1.335 -0.025 0.0
S 0.0 0.0 0.0
H -0.025 1.335 0.0

(...)
                                   SCF - CYCLE
                                   -----------

* Convergence on norm of error vector (gradient).
  Desired convergence:9.000D-09
  Allowed convergence:9.000D-09

* ERGVAL - convergence in total energy
* FCKVAL - convergence in maximum change in total Fock matrix
* EVCVAL - convergence in error vector (gradient)
--------------------------------------------------------------------------------------------------------------------------------
           Energy               ERGVAL    FCKVAL    EVCVAL      Conv.acc    CPU          Integrals   Time stamp
--------------------------------------------------------------------------------------------------------------------------------
It.    1    -222.5040463472      0.00D+00  0.00D+00  0.00D+00               1.09435700s   Atom. scrpot   Mon May 10
It.    2    -399.6076398739      1.77D+02  1.47D+01  1.62D+00              19.40600000s   LL SL SS       Mon May 10
It.    3    -399.8260580215      2.18D-01 -4.55D-01  3.32D-01   DIIS   2   18.90000000s   LL SL SS       Mon May 10
It.    4    -399.8373072830      1.12D-02  1.52D-01  6.53D-02   DIIS   3   18.57200000s   LL SL SS       Mon May 10
It.    5    -399.8377309311      4.24D-04 -2.91D-02  7.20D-03   DIIS   4   18.11500000s   LL SL SS       Mon May 10
It.    6    -399.8377559409      2.50D-05  1.06D-03  2.66D-03   DIIS   5   17.72600000s   LL SL SS       Mon May 10
It.    7    -399.8377611380      5.20D-06  7.13D-04  6.28D-04   DIIS   6   17.58300000s   LL SL SS       Mon May 10
It.    8    -399.8377614035      2.66D-07  1.98D-04  1.21D-04   DIIS   7   17.12700000s   LL SL SS       Mon May 10
It.    9    -399.8377614115      7.96D-09 -5.22D-05  2.53D-05   DIIS   8   16.51600000s   LL SL SS       Mon May 10
It.   10    -399.8377614119      4.26D-10  9.48D-06  6.80D-06   DIIS   9   15.87700000s   LL SL SS       Mon May 10
It.   11    -399.8377614120      4.25D-11 -1.25D-06  1.18D-06   DIIS   9   14.71600000s   LL SL SS       Mon May 10
It.   12    -399.8377614120     -4.49D-12  1.39D-07  4.16D-07   DIIS   9   12.59100000s   LL SL SS       Mon May 10
It.   13    -399.8377614120     -7.56D-12 -5.49D-08  1.54D-07   DIIS   9   10.79300000s   LL SL SS       Mon May 10
It.   14    -399.8377614120      5.46D-12 -2.77D-08  3.38D-08   DIIS   6    9.60800000s   LL SL SS       Mon May 10
It.   15    -399.8377614120      1.30D-11 -5.16D-09  7.89D-09   DIIS   6    7.04400000s   LL SL SS       Mon May 10
--------------------------------------------------------------------------------------------------------------------------------

(...)

             *******************************************************
             ********** Properties for DHF  wave function **********
             *******************************************************



    **************************************************************************
    *************************** Expectation values ***************************
    **************************************************************************

    EFG: XX011       :     1.754199432883 a.u.      s0 = F   t0 = F
    EFG: XX012       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: XY011       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: XY012       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: XZ011       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: XZ012       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: YY011       :    -1.025547572224 a.u.      s0 = F   t0 = F
    EFG: YY012       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: YZ011       :    -2.644477335759 a.u.      s0 = F   t0 = F
    EFG: YZ012       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: ZZ011       :    -0.728651860658 a.u.      s0 = F   t0 = F
    EFG: ZZ012       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: XX021       :    -2.538321928493 a.u.      s0 = F   t0 = F
    EFG: XY021       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: XZ021       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: YY021       :     2.186930090162 a.u.      s0 = F   t0 = F
    EFG: YZ021       :     0.00000000E+00 a.u.      s0 = T   t0 = F
    EFG: ZZ021       :     0.351391838330 a.u.      s0 = F   t0 = F
    ---------------------------------------------------------------------------
    s0 = T : Expectation value zero by point group symmetry.
    t0 = T : Expectation value zero by time reversal symmetry.
----------------------------------------------------------------------------
----------------------------------------------------------------------------
* Electric field gradients :

  ------------------------------------------------------------------------
            Individual (non-zero) components

            Electronic             Nuclear                Total
            contribution           contribution           contribution
  ------------------------------------------------------------------------

  Nucleus: H

  qxx       0.8770997164 au       -1.0168089775 au       -0.1397092611 au
  qyy      -0.5127737861 au        0.5955804527 au        0.0828066666 au
  qyz      -1.3222386679 au        1.4929244299 au        0.1706857620 au
  qzy      -1.3222386679 au        1.4929244299 au        0.1706857620 au
  qzz      -0.3643259303 au        0.4212285248 au        0.0569025945 au

  Nucleus: H

  qxx       0.8770997164 au       -1.0168089775 au       -0.1397092611 au
  qyy      -0.5127737861 au        0.5955804527 au        0.0828066666 au
  qyz       1.3222386679 au       -1.4929244299 au       -0.1706857620 au
  qzy       1.3222386679 au       -1.4929244299 au       -0.1706857620 au
  qzz      -0.3643259303 au        0.4212285248 au        0.0569025945 au

  Nucleus: S

  qxx      -2.5383219285 au       -0.1244976575 au       -2.6628195860 au
  qyy       2.1869300902 au        0.0692406273 au        2.2561707174 au
  qzz       0.3513918383 au        0.0552570303 au        0.4066488686 au


  ------------------------------------------------------------------------
            Total contribution to principal components
  ------------------------------------------------------------------------

  Nucleus: H

  qxx   -.1397092611E+00 au
  qyy   0.2410311026E+00 au
  qzz   -.1013218415E+00 au
  Principal axis to total contribution


  Nucleus: H


               Column   1     Column   2     Column   3
       1       1.00000000     0.00000000     0.00000000
       2       0.00000000     0.73337058    -0.67982909
       3       0.00000000     0.67982909     0.73337058
    ==== End of matrix output ====

  Nucleus: H

  qxx   -.1397092611E+00 au
  qyy   0.2410311026E+00 au
  qzz   -.1013218415E+00 au
  Principal axis to total contribution


  Nucleus: H


               Column   1     Column   2     Column   3
       1       1.00000000     0.00000000     0.00000000
       2       0.00000000     0.73337058     0.67982909
       3       0.00000000    -0.67982909     0.73337058
    ==== End of matrix output ====

  Nucleus: S

  qxx   -.2662819586E+01 au
  qyy   0.2256170717E+01 au
  qzz   0.4066488686E+00 au
  Principal axis to total contribution


  Nucleus: S


               Column   1     Column   2     Column   3
       1       1.00000000     0.00000000     0.00000000
       2       0.00000000     1.00000000     0.00000000
       3       0.00000000     0.00000000     1.00000000
    ==== End of matrix output ====
  ------------------------------------------------------------------------

  1 a.u. =  9.71736E+21 V*m**-2

----------------------------------------------------------------------------
* Nuclear quadrupole coupling constants (principal components):

              Total contribution
  ------------------------------------------------------------------------

  Nucleus: H    Proton charge:  1   Mass:   2   Spin:  1.0   Quadrupole moment:    0.0028600

  Xxx            -0.0938845063 MHz
  Xyy             0.1619726988 MHz
  Xzz            -0.0680881925 MHz
  Eta               0.15926334

  Nucleus: H    Proton charge:  1   Mass:   2   Spin:  1.0   Quadrupole moment:    0.0028600

  Xxx            -0.0938845063 MHz
  Xyy             0.2093868636 MHz
  Xzz            -0.1155023573 MHz
  Eta               0.10324359

  Nucleus: S    Proton charge: 16   Mass:  33   Spin:  1.5   Quadrupole moment:   -0.0678000

  Xxx             2.2256536797 MHz
  Xyy            -3.8397723696 MHz
  Xzz             1.6141186899 MHz
  Eta               0.15926334
  ------------------------------------------------------------------------

  1 a.u. = 234.96474170 MHz

[Juan Jose Aucar]

Dear Marcin Gronowski,

I'm not a Dirac expert but I'll try to answer your question (if u already couldn't solve it - sry for the delay).
To understand how DIRAC performs the EFGs (and NQCCs) calculations you can acces the PROPERTIES section of DIRAC's manual (http://www.diracprogram.org/doc/release-19/manual/properties.html?highlight=nqcc#nqcc) where you can see that a transformation to principal axis is performed, so the way DIRAC treats the molecule symmetry is crucial.
A minor issue is that you were requesting something on the MOLTRA module, but u're not using it (because just a DHF calculation is performed).

I attach two outputs where you can see that calculated values for the NQCCs with no symmetry detection are really close to the experimental ones that you cited. I'm not sure if those values that you are referring to are for the NQCC's on the principal axis of the system.

Best regards,

Juan J. Aucar

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[Marcin Gronowski]

Dear Juan J. Aucar

Thank you for your clarification. The NQCC's, which I quoted,  are on the principal axis of the system. So it seems that I should look into the code to understand what Dirac does with EFG to obtain NQCC.

All the best
Marcin

-----------------------------------------------------------

Marcin Gronowski

https://scholar.google.com/citations?hl=en&user=dyS8l60AAAAJ

Institute of Physical Chemistry
Polish Academy of Sciences
Kasprzaka 44, 01-224 Warsaw, Poland
tel. +48 22 343 33 53

https://ichf.edu.pl/

To view this discussion on the web visit https://groups.google.com/d/msgid/dirac-users/CAAG1oD9%3D%2B1ydHMpUvQ26WtYmHQBe9B3cgaMsGn9f%3DgbntKfx_g%40mail.gmail.com.