Oh, thank you very much, now I understand, I didn't realize that the fch files don't save the occupations.

R.

It is impossible, because .fch format doesn't explicitly record orbital occupation information. You can let Multiwfn export .mwfn or .molden file, in which orbital occupations are recorded in specific field.

Hello, I think I found a little problem in the section of generating (or changing) the file format. When I have a molden file of a system whose orbitals are fractionally occupied (like in a casscf calculation or when using xtb) when I convert it to fch format (it is for ESP calculation, I want to do it using cubegen since the system is too large), the occupations are directly placed as 2.0 and 0.0 and there are no more such fractional occupations. Is it possible that by generating the .fch file the occupation can be maintained?

thanks for the help!

R.