I will make an atomistic simulation of the beta-silicon nitride phase with the GULP code in order to obtain its structural, mechanic and thermodynamic properties; I would like to use fractional coordinates. thank you
Dear Tajouo TELA Herve ,
Here's how I would do this for any material.
- Determine the composition and symmetry of the material. For beta-silicon nitride, this can be determined from its Wikipedia page (https://en.wikipedia.org/wiki/Silicon_nitride). Of course there are better sources, but it's a start!
- Option 1: Search for the material composition and symmetry on Materials Project (see attached image "MaterialsProject.png"). See how I input "Si-N" in the search bar to find all possible compositions and symmetries of silicon nitride. It just so happens that the first entry at the bottom of the page, with a materials Id of "mp-988", is beta-Si3N4 (or at least very close, i.e. with an extra mirror plane along the principal axis of rotation). If you click on that entry, you can download a CIF file, which is viewable in VESTA.
- Option 2: Search for the material composition and symmetry on OQMD (http://oqmd.org/materials/composition/Si3N4). Beta-silicon nitride should be one of the first two entries, 3591 or 68761, which are the most stable (i.e. have the lowest formation energy among all possible Si3N structures) and have the correct symmetry or close to it (i.e. P63 or P63/m). If you click on these entries, you can download a VASP POSCAR file, which is viewable in VESTA.
- Option 3: Search for the material composition and symmetry on AFLOW (http://aflow.org). Using their MendeLIB tool, search for compounds containing "Si & N" but make sure to specify the "# of Species" as 2, otherwise, your search will generate way too many results (see attached image "AFLOW.png"). There are a number of structures with nearly correct symmetry (i.e. 176 - P63/m). Click on them, check their structures, and see if one of them is what you are looking for. There will be an option to save a CIF file.
- Option 4: Search for the materials composition and symmetry on ICSD, the International Crystal Structure Database, which is a curate database of experimental crystal structures with detailed information (not always super accurate) about the experimental conditions and setup. The databases in options 1-3 are free to use; Materials Project asks that you create an account with your email. ICSD requires a license though many universities acquire it.
There are even more ways to determine, find, or construct a crystal structure. With that being said, these options are probably the easiest to learn/use and will get you viewing beta-silicon nitride in no time!
I hope this was helpful, please let me know if you have any further questions.
Best,
Rob
https://en.wikipedia.org/wiki/Silicon_nitride
https://materialsproject.org/materials/mp-583712/
download the cif file and open in vesta and you are done. You can also change some parameters if you want.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Thermodynamics