# Electrostatic potentials from calculated densities

**URL:** <https://discuss.avogadro.cc/t/electrostatic-potentials-from-calculated-densities/4026>\
**Category:** Suggestions\
**Created:** [October 25, 2022, 8:23pm UTC](https://discuss.avogadro.cc/t/electrostatic-potentials-from-calculated-densities/4026 "2022-10-25T20:23:37Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![seal](https://discuss.avogadro.cc/user_avatar/discuss.avogadro.cc/seal/32/1234_2.png) [@seal](https://discuss.avogadro.cc/u/seal)\
**Post date:** [October 25, 2022, 8:23pm UTC](https://discuss.avogadro.cc/t/electrostatic-potentials-from-calculated-densities/4026/1 "2022-10-25T20:23:37Z")

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In JMol I can map MEP over the density matrix

```auto
isosurface furansp.eldens.cube map furansp_mep.cube

```

To get something like this:

 ![image](https://discuss.avogadro.cc/uploads/default/original/2X/a/ab1ee3a6d2b08483c43c6ba1465bff2122163c60.jpeg)

However, AFAIK, you cannot increase “quality” of the isosurface (smoothness). Avogadro2 renders Electrostatic Potentials in a much more pleasant way:

 ![image](https://discuss.avogadro.cc/uploads/default/original/2X/2/26f6abe65eee93e918a22a2b3b447588b7a7441e.jpeg)

But is there a way to feed it the values from calculations and not use approximations?

There seems to be some option file-related, but it’s uninformative as of now

 ![image](https://discuss.avogadro.cc/uploads/default/original/2X/6/645c18f9a491d518f6601342fb7abc6a39974d0d.png)

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<div class="post-metadata">

**Author:** ![ghutchis](https://discuss.avogadro.cc/user_avatar/discuss.avogadro.cc/ghutchis/32/456_2.png) [@ghutchis](https://discuss.avogadro.cc/u/ghutchis)\
**Post date:** [October 25, 2022, 9:45pm UTC](https://discuss.avogadro.cc/t/electrostatic-potentials-from-calculated-densities/4026/2 "2022-10-25T21:45:32Z")

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At the moment if you read in an ESP cube, I’m not sure it tags the cube as ESP.

It won’t be too hard to map cubes from files as properties to color - there just wasn’t enough time over the summer for @aerkiaga to do that.

As a few other posts have indicated, the Surfaces dialog needs some thorough refinement (e.g., the empty menu).

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**Author:** ![Thomas](https://discuss.avogadro.cc/user_avatar/discuss.avogadro.cc/thomas/32/3403_2.png) [@Thomas](https://discuss.avogadro.cc/u/Thomas)\
**Post date:** [November 1, 2022, 7:41am UTC](https://discuss.avogadro.cc/t/electrostatic-potentials-from-calculated-densities/4026/3 "2022-11-01T07:41:44Z")

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> [@seal](#):
>
> However, AFAIK, you cannot increase “quality” of the isosurface (smoothness).

In addition to the public archives of [Jmol user mailing list](https://sourceforge.net/p/jmol/mailman/jmol-users/) (and the possibility to address a new question, [jmol-users@lists.sourceforge.net](mailto:jmol-users@lists.sourceforge.net)), the documentation about [surfaces](http://wiki.jmol.org/index.php/Surfaces) in general yields [examples of MEP](https://chemapps.stolaf.edu/jmol/docs/examples-11/surfacedemos.htm#MolecularElectrostaticPotentials) (entries 8, 9, 10) with the syntax (on Jmol’s console) of e.g.,

```java
load C6H6.smol;moveto 1.0 { -962 -235 -141 56.81}
isosurface resolution 6 molecular map mep

```

By `resolution 6`, there is an example that (to some degree) the tesselation of the surface s adjustable. Of course, the more triangles to define, the more work for the program.

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<div class="post-metadata">

**Author:** ![ghutchis](https://discuss.avogadro.cc/user_avatar/discuss.avogadro.cc/ghutchis/32/456_2.png) [@ghutchis](https://discuss.avogadro.cc/u/ghutchis)\
**Post date:** [November 4, 2022, 2:57pm UTC](https://discuss.avogadro.cc/t/electrostatic-potentials-from-calculated-densities/4026/4 "2022-11-04T14:57:20Z")

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> [@Thomas](#):
>
> By `resolution 6`, there is an example that (to some degree) the tesselation of the surface s adjustable. Of course, the more triangles to define, the more work for the program.

One part of @aerkiaga work this summer was to add mesh smoothing. So you don’t always need a higher resolution. Some minimal smoothing usually works better and faster than an increased resolution.