Multiwfn forum

asenruhup@hotmail.com

Member

Registered: 2019-04-14

Posts: 6

spin density visualization

Hellow Prof. Tian Lu,
I have been trying to plot the spin density with MultiWfn 3.7, but nothing appeared on the screen (option 5/5/3)
I departed from a .wfx G16 file with the option pop=(spinnatural)

Thanks in advance

Dr. Saturnino Calvo Losada
Dep. Physical Chemistry/
Universidad de Málaga

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,760

Website

Re: spin density visualization

Please simply remove pop=(spinnatural).

Also note that after calculating grid data, isosurface map is not automatically shown. To visualize isosurface, you should select option -1.

asenruhup@hotmail.com

Member

Registered: 2019-04-14

Posts: 6

Re: spin density visualization

Hi again,
I could obtain plots with alfa and beta regions for the spin density with u-DFTs WFN

Nevertheless, with CASSCF wavefunctions (from G16 package) only alfa plots are yielded.

How can be this remedied?

Best regards

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,760

Website

Re: spin density visualization

In principle it is impossible to obtain spin density from CASSCF wavefunction.
If you would like to examine distribution of unpaired electron for CASSCF wavefunction, it is recommended to use Multiwfn to calculate odd electron density (OED), see Section 4.A.6 of Multiwfn manual for introduction and how to do.

asenruhup@hotmail.com

Member

Registered: 2019-04-14

Posts: 6

Re: spin density visualization

Hellow Prof. Tian Lu,
I have been using extensively OED, but now with .wfx obtained from ORCA. In order to mimic the spin density for CASSCF wfn, the OED is what you recommeded to me. In the case of Gaussian 2016, it was necessary guess=mix, is there any option of this kind which sould be done in ORCA?
Another question, I suppose that once you have obtained the OED function, it could be analyzed as the rho and the laplacian of rho is done within the AIM context (contour plots, envelopes, CPs. and so on)

Thanks a lot

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,760

Website

Re: spin density visualization

1 If you just need OED of CASSCF wavefunction, even if you are using Gaussian 16, guess=mix is never needed. guess=mix is useful to obtain broken-symmetry UKS wavefunction. For CASSCF, only one set of orbitals (rather than alpha and beta spin orbitals) is used as initial guess, therefore guess=mix doesn't make sense.

2 After generating grid data of OED by Multiwfn, for this function you can perform topology analysis using main function 2, perform basin analysis using main function 17, and plot it as plane map via main function 4. To do this, before booting up Multiwfn you need to set "iuserfunc" in settings.ini to -1 or -3; in this case, the user-defined function will corresponds to linear or B-spline interpolated function based on grid data in memory. After that, in the aforementioned functions, you can choose user-defined function as the function to be analyzed or plotted.

To successfully perform topology analysis for a function with relatively complicated distribution such as OED, some tricks are needed, see Sections 4.2.2, 4.2.10 and 4.2.11 of Multiwfn manual for discussions and examples. For basin analysis of a general function like OED, see Sections 4.17.2, 4.17.3 and 4.17.4 for illustrations.