Expand information on crest

README.md

@@ -1,45 +1,61 @@
 # avo_xtb
-This plugin adds an interface to the xtb program in Avogadro 2.
+This plugin adds an interface to the xtb program in Avogadro 2, as well as the CREST program for extended functionality.
 
 [`xtb`](https://github.com/grimme-lab/xtb) is developed by the Grimme group in Bonn and carries out semi-empirical quantum mechanical calculations using the group's e**x**tended **T**ight-**B**inding methods, referred to as "GFNn-xTB".
 
 These methods provide fast and reasonably accurate calculation of **G**eometries, **F**requencies, and **N**on-covalent interactions for molecular systems with up to roughly 1000 atoms, with broad coverage of the periodic table up to *Z* = 86 (radon).
 
+[`crest`](https://github.com/crest-lab/crest) (Conformer–Rotamer Ensemble Sampling Tool) adds a variety of sampling procedures for several interesting applications including conformer searches, thermochemistry, and solvation.
+
 # Capabilities
 
 This plugin currently provides functionality to run the following calculation types and view the results directly in Avogadro:
+
+### xtb
 * single point energies
 * geometry optimizations
 * vibrational frequencies
 * molecular orbitals
 * molecular dynamics
-* conformer searches (via [crest](https://github.com/crest-lab))
 
 There is also the option to submit a custom command to `xtb`, permitting any calculation to be run, though the output is in this case only parsed for results of the basic calculation types.
 
+### CREST
+* conformer searches
+
 # Requirements
 
 ### xtb
 
-Currently, the plugin does not download the `xtb` binary automatically, and they are not bundled with Avogadro. `xtb` (and `crest` for conformer searches) must be obtained separately. There are five options that will make `xtb` visible to the extension:
+Currently, the plugin does not download the `xtb` binary automatically, and it is not bundled with Avogadro. Instead, it must be obtained separately. There are five options that will make `xtb` visible to the extension:
 1. Install xtb with `conda` from conda-forge and use Avogadro with the `conda` environment, either by setting it in the Python settings or by starting Avogadro with the environment activated
 2. Manually download the `xtb` binary and put it into the system PATH
 3. Manually download `xtb` and place it entirely within the `Avogadro/commands/avo_xtb/` directory
 4. Manually download `xtb` and manually specify its location in the `Configure...` menu
 5. Use the "Get xtb..." function within Avogadro after installing this extension
 
-`xtb` and `crest` are distributed by the Grimme group under the LGPL license v3. The authors of Avogadro and avo_xtb bear no responsibility for xtb or crest or the contents of the Grimme group's repositories. Source code for the programs is available at the repositories linked above.
+### CREST
+
+While `xtb` is cross-platform, `crest` is distributed only for Linux/UNIX systems. As a result, Windows and macOS users of the plugin will not have the calculations that rely on CREST available to them in the Avogadro interface.
+
+`crest` can be made visible to the plugin in the same ways as for `xtb` listed above. If method 3 is used, `crest` should be located at `Avogadro/commands/avo_xtb/bin/crest`. The "Get xtb..." option within Avogadro will also download `crest` on supported operating systems.
 
 ### Open Babel
 
-The plugin also relies on Open Babel for conversion of output files to Avogadro's `cjson` format. The path to the `obabel` binary can be specified in the `Configure...` menu if it is not automatically detected. If you use Avogadro on Windows, macOS, or the AppImage or Flatpak on Linux, you have a recent build of `obabel` with CJSON support in the same folder as the Avogadro executable. If you have obtained it from a distro's repositories, your version of `obabel` ***does not*** have the necessary CJSON support, and you will unfortunately have to compile it yourself from the [latest code](https://github.com/openbabel/openbabel).
+The plugin also relies on Open Babel for conversion of output files to Avogadro's `cjson` format. The path to the `obabel` binary can be specified in the `Configure...` menu if it is not automatically detected.
+* If you use Avogadro on Windows, macOS, or the AppImage or Flatpak on Linux, you have a recent build of `obabel` with CJSON support in the same folder as the Avogadro executable, and you should use that. The plugin should hopefully find it automatically.
+* If you have obtained it from a distro's repositories, your version of `obabel` ***does not*** have the necessary CJSON support, and you will unfortunately have to compile it yourself from the [latest code](https://github.com/openbabel/openbabel).
+
+# Disclaimer
+
+`xtb` and `crest` are distributed by the Grimme group under the LGPL license v3. The authors of Avogadro and avo_xtb bear no responsibility for xtb or CREST or the contents of the respective repositories. Source code for the programs is available at the repositories linked above.
 
 # Cite
 
 For GFN2-xTB (default method):
 * C. Bannwarth, S. Ehlert and S. Grimme., *J. Chem. Theory Comput.*, **2019**, 15, 1652-1671. DOI: [10.1021/acs.jctc.8b01176](https://dx.doi.org/10.1021/acs.jctc.8b01176)
 
-For CREST (conformer searches):
+For CREST:
 * P. Pracht, F. Bohle, S. Grimme, *Phys. Chem. Chem. Phys.*, **2020**, 22, 7169-7192. DOI: [10.1039/C9CP06869D](https://dx.doi.org/10.1039/C9CP06869D)
 
-See the xtb GitHub repository for other citations.
+See the xtb and CREST GitHub repositories for other citations.