Multiwfn forum

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,830

Website

Multiwfn and CP search between atom

Below is a question asked by a Multiwfn user via E-mail, considering other users may also encounter this problem, I copy the question and my reply in this post

I'd like to ask a short question about your Multiwfn program. I computed a set of critical points and bond paths, according to the QTAIM theory. Is there a simple way to determine which critical points belong to which bond (that is in-between which atoms such CP is located)? When saving a detailed data into the CPprop.txt this information if not present, doing it by hand or using the Multiwfn visualiser is very troublesome since the molecule is very large

My reply

Here I take water as an example.
We first locate its CPs and generate bond paths, then go to "-5 Modify or print detail or export paths, or calculate property along a path", select "1 Print summary of paths", you will see

#    1     CP:    4 (3,-1) ---> CP:    2 (3,-3)   Length:  1.41000
#    2     CP:    4 (3,-1) ---> CP:    1 (3,-3)   Length:  0.27000
#    3     CP:    5 (3,-1) ---> CP:    3 (3,-3)   Length:  0.27000
#    4     CP:    5 (3,-1) ---> CP:    2 (3,-3)   Length:  1.41000

It is shown that CP4 links CP1 and CP2 via bond path #1 and #2. Then return to main menu of topology analysis and select option 0, you will see below information on console window

Summary of found CPs:
  Index               XYZ Coordinate (Bohr)               Type
     1    -0.000000000    -1.381088249    -0.863018600   (3,-3)  Nuc:    3(H )
     2    -0.000000000    -0.000000000     0.225448153   (3,-3)  Nuc:    1(O )
     3     0.000000000     1.381088249    -0.863018600   (3,-3)  Nuc:    2(H )
     4    -0.000000000    -1.139059094    -0.680319212   (3,-1)
     5     0.000000000     1.139059094    -0.680319212   (3,-1)

Clearly, CP1 and CP2 correspond to H3 and O1, respecitvely. Thus CP4 is bond critical point between H3 and O1.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,830

Website

Re: Multiwfn and CP search between atom

Q:

is it possible to compute critical points and bond paths only for selected pairs of atoms? Out of more than 400 BCps only 5 are of interest for me, and looking for those every time for multiple structures is a pain.

A:

You can select "1 Search CPs from a given starting point", then input index of two atoms, then midpoint of these two atoms will be used as starting point for searching CPs. I think this mode should be appropriate for your case.