Multiwfn forum

alessiomacorano

Member

Registered: 2023-12-19

Posts: 18

ESP and Electric field evaluation on a molecule

Dear Prof Tian Lu,

Thank you so much for your impressive work about multiwfn as well as the forum.

I have a question about the ESP and electric field evaluation on a molecule.

Shortly here I attach the figure 2 of the paper (DOI: 10.1021/acs.jcim.8b00563), where the authors compute the Electrostatic potential and electric field values on a grid of points in a plane 3.25 Å from the plane of each heterocycle within the van der Waals projection of the heterocycle and they get the ESPmin, ESPmax and Fmax.

I am wondering if in Multiwfn I will be able to do something like this.

Thank you so much for your time and efforts

My best

Alessio

sobereva

Tian Lu (Multiwfn developer)

From: Athens, Greece

Registered: 2017-09-11

Posts: 2,291

Website

Re: ESP and Electric field evaluation on a molecule

Dear Alessio,

This question involves many technique points, I will explain in turn below.

* Multiwfn is able to plot ESP 2D map in any plane, including the plane you mentioned, see Section 4.4.4 of Multiwfn manual for example, and the grid data of the entire plane can be exported to a .txt file in the post-processing menu.

* Multiwfn is unable to directly plot 2D map in the plane for a real space function only within vdW surface projection region, however there is workaround. You can use Multiwfn to generate an image file of 2D map of ESP in the entire plane that 3.25 Å from the molecule, and generate an image file representing vdW surface in the molecular plane (i.e. rho=0.001 a.u. contour line. See the bold blue line in the example in Section 4.4.4). Then, use photoshop or AI tool (gemini, etc.) to remove content of the first map that outside the contour line of the second map.

* I don't know how ESPmin and ESPmax were exactly defined in that paper. I would like to mention that Multiwfn is not only able to determine minima and maxima of any selected real space function over the entire 3D molecular vdW surface, but also able to determine those on a contour line of a given real space function in a 2D plane, see Section "4.4.12 Showing extrema of a function on contour line" of manual for example. Perhaps you can achieve your aim by properly using these features.

* Electric field is a vector rather than a scalar field. However, user-defined function 103 in Multiwfn directly corresponds to magnitude of electric field (norm of the vector), see corresponding part of Section 2.6 of manual. You can use similar way as mentioned above to study electric field magnitude.

Best regards,

Tian