Multiwfn forum

Hi all,

I need to calculate Coulomb and four-center integrals between specific orbitals from different molden files.

1- The Coulomb integrals are different from the usual Coulomb integrals between electronic orbitals, in this case the integrals are:
(ii'|jj') = int ( phi_i(r1) phi_i'(r2) r12 phi_j(r1) phi_j'(r_2) )dr1 dr2

the molecular orbitals phi_i(r1) and phi_j(r1) are from the same molden file, while both orbitals phi_i'(r2) and phi_j'(r2) are saved in other molden file.

2- The four-center integrals are a specific case of overlap integrals, in this case the integrals are:

S_(iji'j') = int ( phi_i(r) phi_j(r) phi_i'(r) phi_j'(r) )dr

phi_i and phi_j are molecular orbitals from the same molden file, phi_i' and phi_j' are molecular orbitals from other molden file as in the case of Coulomb integrals.

I am sending in this message also the equations of Coulomb integral (coulomb_integral.jpeg) and four-center integral (four_center_integral.jpeg) attached.

Is there any way to calculate this special cases of coulomb and four-center integrals with Multiwfn code?

Hi all,

Does anyone know how to computationally calculate the Fourier transform of the product of two molecular orbitals?  I have molecular orbitals at position space obtained from quantum calculations, and I need the Fourier transform of product of orbitals.

Thanks,

Mateus

Hi all,

I need to calculate the overlap between two specific orbitals obtained with UHF calculation for a system compused by 10 water molecules,
one additional electron and one positron. In this calculation, I positioned GTF's for electrons on atom coordinates, and also a extra expansion center on origin (center of cavity). The GTF's positioned on atom coordinates (6-31G+(d,p)) and on origin (aug-cc-pVTZ) are different.

For the positron I positioned just one expansion center on origin with the same GTF (aug-cc-pVTZ) used for extra center of electrons. Therefore, the electronic wave function has different GTF's (6-31G+(d,p) and aug-cc-pVTZ) than positronic wave function (aug-cc-pVTZ). I have separate molden files  for beta electrons, alpha electrons and the positron.

My question is:

Is there some problem to create just one .wfn file for alpha electrons and positron, and use this file to calculate overlap between alpha orbital with positron orbital using the function "3.200.10 Output various kind of integral between orbitals"? Is this function use the information of GTF's to calculate the overlap?

Thanks for the attention,

Mateus Bergami

Hi everyone,

My question is how could I convert two .molden files from alpha and beta orbitals into just one .wfn file? I know how to convert just one .molden file into a .wfn with Multiwfn program.

I need this .wfn to calculate the spin density of electrons, because actually I have a .molden of alpha electrons and other for beta electrons.

Thanks,

Mateus Bergami