You need to write your own code in "function userfunc" in function.f90, and then compile Multiwfn yourself. This is very easy. After that, your customized function can be studied as a built-in user-defined function.

Best regards,

Tian

I need to calculate the integral of the following real space functions:
x**2, y**2, z**2,  x*y, x*z, y*z,
with the electron density rho(r) of some molecular orbitals.
Is it possible? If yes - how can I do it with Multiwfn?

(I looked in the user-defined functions and found that
I can calculate only (x**2 + y**2 + z**2) with rho(r) - this is number 3 or 6,
or x, y, z numbers 21, 22, 23, but I have not found x**2 * rho(r) etc.)

Thank you in advance,

Sincerely yours,
Alexander Nikolaev