Multiwfn forum

mamin

Member

Registered: 2022-06-12

Posts: 5

Oxidation States

Dear All,
I have a question about the calculation of the oxidation states using LOBA. I get a different answer if I change the threshold. I have a Mn cluster of 4 Mn in different oxidation states. When I use 50% for the threshold I get 3 Mn in the Mn(III) states and 1 in the Mn(IV). However, if I make the threshold 80% then I get 3 Mn (IV) and one Mn(III). I don't know how to judge each of these calculation.
Please let me know what do you think?
Thank you

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: Oxidation States

Usually a threshold around 50% is appropriate, 80% is excessively large.

mamin

Member

Registered: 2022-06-12

Posts: 5

Re: Oxidation States

Thank you very much. What does it mean chemically when you say "80% is excessively large"? How do I evaluate if my choice for the threshold?

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: Oxidation States

This threshold is used to determine if electrons of a localized molecular orbital (LMO) should be fully attributed to an atom (or user-defined fragment). For example, if you set it to 50%, then if contribution of an atom to a doubly occupied LMO is greater than half, then all the two electrons will be attributed to formal electron population of the atom. It is obvious that if the threshold is too strict, for example, as large as 80%, then it is very likely that formal electron population of atoms may be underestimated, and hence oxidation states tend to be overestimated. If you are still confused, I suggest you reading original paper of LOBA.