6.5 Check sanity of wavefunction

The input files of Multiwfn generated by various quantum chemistry codes are not always standard. For example, .molden file generated by many programs are problematic in content or format. After feeding them to Multiwfn and you want to make sure if the wavefunction has been correctly loaded, there are two useful ways to check sanity:

• (1) Enter main function 100 and select subfunction 4, then choose electron density. If the integral of electron density over the whole space is very close to the actual number of electrons, then the wavefunction is ready for use.

• (2) Enter main function 1000 (a hidden function) and select subfunction 100. This function will check satisfaction of normalization condition of all orbitals, and show you the maximum deviation to unity and integer. If both the two maximum deviations are evidently larger than zero, then there must be some severe problems in the input file; if any one of them is very close to zero, the input file should be fully compatible with Multiwfn. Because in Multiwfn the orbital coefficients with respect to both GTFs and basis functions are available if the inputted wavefunction file contains basis function information, in this case this function will ask you to choose examining which kind of orbital coefficients (of course, both of them should satisfy the normalization condition).