Multiwfn forum

vinimart

Member

Registered: 2019-09-03

Posts: 7

topology and basin analysis.

Hello guys.
I'm a new worker with this tool and i'm loving it.
So my doubt might be dumb, but please help me.
When i go to basin analysis, electron density, hamiltonian kinetic energy density K(r), i get basin energies that when added all up give me a value very close to the single point energy calculation value obtained with ORCA or GAMESS wich is great.
When i go to topology analysis with electron density (analytical Hessian) as real space function chosen, and then output the properties for my molecule critical points, the energy values do not match the K(r) values from the basin analysis. Why is that? I imagined that the energy value for a certain atom basin should be the same regardless i use K(r) from basin analysis or topology analysis.
I also want to study the electron density change that a bond suffers when my molecule changes it's conformation. Can i use the density of all electrons from the CPprop.txt file gotten from topology analysis?
Thank you very much.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,773

Website

Re: topology and basin analysis.

The crticial point properties characterize real space functions at a specific point, however the value outputted by basin analysis corresponds to the integral of a selected real space function over the whole basin, clearly their values must be very different. In other words, topology analysis focuses on revealing real space function values at some featured points, while basin analysis focuses on revealing total distribution amount of real space functions in certain local regions.

There is no unique way of defining electron density of a bond. However, as the bond critical point is often regarded as the most representative point of a bond, you can study difference of electron density at BCP of a bond between different conformers to study how conformation change affects the electron density distribution on the corresponding bonding region.

vinimart

Member

Registered: 2019-09-03

Posts: 7

Re: topology and basin analysis.

I see.
Thank you so much.