Multiwfn forum

akagomes

Member

Registered: 2024-10-10

Posts: 1

Calculation of gyration radius of spin density

Hi!

I just started using multiwfn and I want to calculate the gyration radius of a spin density in cube file format (system contains water molecules and an excess electron). I tried the following instructions (manual 3.8):

200 // Other function (Part 2)
11 // The present function
3 // Select a real space function
5 // Spin density
2 // Calculate center of spin density
y // Take the calculated center for evaluating various data in option 1
1 // Evaluate various data for spin density

First, there no spin density option for me to select. Also, if I choose options 1 or 100 (electron density or user defined function) the output value does not make any sense.

My spin density file was generated by cp2k and the calculation used periodic boundary conditions. Does anyone know how should I proceed to get the correct value for the gyration radius?

Last edited by akagomes (2024-10-10 14:09:57)

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 2,011

Website

Re: Calculation of gyration radius of spin density

Your precedure is only correct when your input file contains wavefunction information. Given that you used .cub file recording spin density as input file, you need to ask Multiwfn to calculate spin density via interpolation of loaded grid data. So, you should set "iuserfunc" in settings.ini to -1 (3D linear interpolation), after entering subfunction 11 of main function 100, choose the option "3 Select the function to be studied", select "100 User-defined function", and then start calculation by corresponding option.

Alternatively, directly using the .molden file exported by CP2K as input file of Multiwfn, then you can exactly follow the commands in the manual. See Section 2.5 of Multiwfn manual for more information about input file.