Multiwfn forum

Sunghwan Choi

Member

Registered: 2020-06-18

Posts: 5

Quadrapole and octupole

Hi, I'm a newbie.
In order to calculate electric quadrupole and octupole from the density matrix, I need quadrupole and octupole momentum matrices
For dipole moment, Manual (section 3.200.2) tells details but I cannot find how to build quadrupole and octupole momentum matrices.
Is it possible to build those matrices through Multiwfn?

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,852

Website

Re: Quadrapole and octupole

Multiwfn doesn't have a function to export electric quadrupole and octupole momentum integral matrices. If you want to calculate molecular electric quadrupole and octupole based on a given wavefunction file, I can add a new function to Multiwfn to realize this.

Sunghwan Choi

Member

Registered: 2020-06-18

Posts: 5

Re: Quadrapole and octupole

Yes!! I need it!!   I really appreciate for adding those features~ Can you estimate the development period for those features?

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,852

Website

Re: Quadrapole and octupole

I have updated Multiwfn 3.7(dev) on Multiwfn website. Now using subfunction 2 of main function 15, molecular dipole/quadruple/octopole moments will be outputted at the end. For example, using examples\uracil.wfn as input file, the outputted information is (all units are a.u.)

              *****  Molecular dipole and multipole moments  *****
 Total number of electrons:     58.000039
 Molecular dipole moment (a.u.):       0.473288      1.823815      0.000736
 Molecular dipole moment (Debye):      1.202978      4.635675      0.001871
 Magnitude of molecular dipole moment (a.u.&Debye):      1.884225      4.789221
 Molecular quadrupole moments (Standard Cartesian form):
 XX=  -43.878912  XY=    1.812527  XZ=   -0.000544
 YX=    1.812527  YY=  -28.230912  YZ=   -0.004829
 ZX=   -0.000544  ZY=   -0.004829  ZZ=  -34.463390
 Molecular quadrupole moments (Traceless Cartesian form):
 XX=  -12.531761  XY=    2.718791  XZ=   -0.000816
 YX=    2.718791  YY=   10.940239  YZ=   -0.007244
 ZX=   -0.000816  ZY=   -0.007244  ZZ=    1.591522
 Magnitude of the traceless quadrupole moment tensor:   13.644701
 Molecular quadrupole moments (Spherical harmonic form):
 Q_2,0 =   1.591522   Q_2,-1=  -0.008364   Q_2,1=  -0.000942
 Q_2,-2=   3.139390   Q_2,2 = -13.551565
 Magnitude: |Q_2|=   14.001204
 Molecular octopole moments (Cartesian form):
 XXX=  14.09463  YYY=   8.61373  ZZZ=   0.00275  XYY=   6.66406  XXY=  46.41021
 XXZ=  -0.00991  XZZ=   2.78071  YZZ=  -7.68402  YYZ=   0.01589  XYZ=  -0.00333
 Molecular octopole moments (Spherical harmonic form):
 Q_3,0 =  -0.006233  Q_3,-1= -52.517080  Q_3,1 =  -5.900743
 Q_3,-2=  -0.012895  Q_3,2 =  -0.049957  Q_3,-3= 103.261734  Q_3,3 =  -4.662433
 Magnitude: |Q_3|=  116.093019

You can use any input file containing GTF information for this function, for example, wfn/wfx/mwfn/fch/molden/gms. Note that the data is not calculated based on density matrix, but calculated based on the orbitals in the input file.

Sunghwan Choi

Member

Registered: 2020-06-18

Posts: 5

Re: Quadrapole and octupole

I really appreciate your effort!
I have two questions. 1) is it possible to get quadrupole octupole moment matrices through Multiwfn? I have density matrices in an unusual format. so I want to read the density and operator matrix and calculate matrix multiplication with operator and get a trace of it.
2) I downloaded and check the 3.7(dev) source file but I couldn't find quadrupole/octupole moment integral functions in integral.f90 which I expect to contain the functions. Did you only upload binary files? (I didn't check binary yet)

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,852

Website

Re: Quadrapole and octupole

1 Currently it is not possible. But I will try to find time recently to implement this feature, then I will let you know here. (It is expected I can finish within one week)

2 This part of code is realized in fuzzy.f90.

Sunghwan Choi

Member

Registered: 2020-06-18

Posts: 5

Re: Quadrapole and octupole

Thank you so much. I will be waiting for your notice~

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,852

Website

Re: Quadrapole and octupole

I am glad to inform you that the function you need has been finished.
I just updated Multiwfn 3.7(dev) on Multiwfn website, in subfunction 7 of main function 6, now you can select to export electric quadrupole and octopole moment integral matrices to a text file.
In addition, subfunction 5 is newly added in main function 300, it is able to calculate electric dipole, quadrupole, octopole moments very quickly and analytically based on current density matrix and integral matrices.

Sunghwan Choi

Member

Registered: 2020-06-18

Posts: 5

Re: Quadrapole and octupole

Thanks~ I checked what you did!
It works fine!