Multiwfn forum

amin.alibakhshi@hotmail.c

Member

Registered: 2019-08-25

Posts: 23

computation of atomic radii and molecular surfaces via QTAIM

Hi everyone,
I have a question regarding the quantum theory of atomes-in-molecules implemented in Multiwfn.
I am interested to approximate the total surface of a molecule as well as an estimation of atomic radii in a specific molecule based on this method/basin analysis. I would be so thankful for any hint.
Best regards,
Amin Alibakhshi

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,777

Website

Re: computation of atomic radii and molecular surfaces via QTAIM

Dear Amin Alibakhshi,

I don't well understand your problem. AIM doesn't provide an unambiguous definition of atomic radius and surface.

Best,

Tian

amin.alibakhshi@hotmail.c

Member

Registered: 2019-08-25

Posts: 23

Re: computation of atomic radii and molecular surfaces via QTAIM

Dear Amin Alibakhshi,

I don't well understand your problem. AIM doesn't provide an unambiguous definition of atomic radius and surface.

Best,

Tian

thanks a lot prof. Lu for your response. I had read some papers which used AIM to compute atomic radii but I cannot find them. Apart from using AIM, can Multiwfn somehow give a quantum mechanically computed estimation of atomic radii? I heard it is possible but I cannot find much details on it in the manual. 
Best,
Amin

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,777

Website

Re: computation of atomic radii and molecular surfaces via QTAIM

Dear Amin,

It is possible to calculate radius of isolated atom/ion using Multiwfn based on isosurface of rho=0.001 a.u., however this is not directly applicable to atoms in molecular environment.

Multiwfn is able to calculate volume (V) of atoms in a molecule, if you simply assume that V=4/3*pi*r^3, then the (effective) radius (r) may be estimated.

Best,

Tian

amin.alibakhshi@hotmail.c

Member

Registered: 2019-08-25

Posts: 23

Re: computation of atomic radii and molecular surfaces via QTAIM

Dear Amin,

It is possible to calculate radius of isolated atom/ion using Multiwfn based on isosurface of rho=0.001 a.u., however this is not directly applicable to atoms in molecular environment.

Best,

Tian

Dear Tian,
Can some sort of on-the-fly optimization of atomic radii in a way to give the highest overlap between the generated vdW surfaces using those radii and calculated basins, be a potential solution?
I would highly appreciate your comments on that.
Best,
Amin

amin.alibakhshi@hotmail.c

Member

Registered: 2019-08-25

Posts: 23

Re: computation of atomic radii and molecular surfaces via QTAIM

I found what I was looking for and noticed it is already implemented in the Multiwfn (e.g. example of page 699).
Many thanks for developing such an amazing code
Best,
Amin