Multiwfn forum

monthem

Member

Registered: 2025-03-29

Posts: 9

Criteria for assigning ELF basin labels

Dear professor Tian,

May I kindly ask what are the criteria the programme uses to assigns whether a given ELF basin is for example V(A) or V(A,B)? I am running into some peculiar cases where the program finds many V(A,B) basins with very high sum total populations (up to 6 electrons). This is happening in what I assume to be a highly ionic bond and I believe that it is actually the case that they are all V(A) and not V(A, B) basins. Visualizing ELF.cub file also doesn't show any separate basin between A and B, but one valence basin on A (and just core on B) that diminishes as the isovalue is increased.

I would like however to be able to confirm that the labels may be mistakenly assigned before discussing them.

Kind regards

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 2,000

Website

Re: Criteria for assigning ELF basin labels

If a valence basin directly contacts core basin of A, core basin of B, core basin of C... then this valence basin will be assigned as V(A,B,C...). I think this assignment is reasonable, at least there is no evidently better way.

The situation you noted is common. For example, for NaCl, there is a ELF basin assigned by Multiwfn as V(Na,Cl), which contains all valence electrons of Cl-. But it is indeed a disynatpic basin, because it contacts both core basins of Na and Cl.

V(A,B,C...) doesn't necessarily imply that the electrons in this valence basin must contribute to covalent bond between A, B, C...

If you believe the automatically assigned labels are not expected, you can manually assign the labels by visualizing the basins or isosurfaces.

monthem

Member

Registered: 2025-03-29

Posts: 9

Re: Criteria for assigning ELF basin labels

Dear professor,

Thank you kindly for your quick response.