VelCrys

VelCrys: Interactive web-based application to compute acoustic wave velocity in crystals and its magnetic corrections

Authors: P. Nieves, I. Korniienko, A. Fraile, J.M. Fernández-Díaz, R. Iglesias, D. Legut

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WHAT IS VelCrys?

VelCrys is a web-based interactive tool, that allows to perform further post-processing of the elastic tensor in order to compute and plot the group velocity of the acoustic waves for any crystal symmetry. We also implemented the calculation of effective magnetic corrections to the elastic tensor and corresponding fractional change in group velocity under a magnetic field.

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ONLINE ACCESS

The application can be used online in the following link:

http://www.md-esg.eu/velcrys/

Note that this visualization tool can also be used offline by running it on your local computer, see details below.

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OFFLINE AND DEVELOPER MODE

VelCrys can also be executed in your local computer. It requires to have Python3(>=3.6). For example, in Ubuntu Linux machine you can check the installed version of python3 by opening a terminal and typing

python3 --version

In case you need to install python3 in your machine, you can type

sudo apt-get update
sudo apt-get install python3

Additionally, you need to install the following dependencies

dash(>=2.13.0)
plotly(>=5.17.0)
numpy(>=1.18.4)

you can easily install them with pip3

pip3 install dash
pip3 install plotly
pip3 install numpy

If you need to install pip3 on Ubuntu Linux, then type

sudo apt-get update
sudo apt-get install python3-pip

Once all depencencies are installed, download and extract the velcrys-master.zip file, go to the folder that contains the file velcrys.py and type

python3 velcrys.py

then visit http://127.0.0.1:8050/ in your web browser to use VelCrys.

Compatibility issues

On modern Linux, pip (pip3) may block global installs. A possible solution could be to use a virtual environment (venv):

python3 -m venv .venv
source .venv/bin/activate
pip install <package_name>

Depending on the version of Dash, it may be needed to replace the last line in the velcrys.py file "app.run_server(debug=True)" with "app.run(debug=True)".

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DOCUMENTATION AND CITATION OF VelCrys

More details and examples of this application can be found in the published article:

P. Nieves, I. Korniienko, A. Fraile, J.M. Fernández-Díaz, R. Iglesias, D. Legut, VelCrys: Interactive web-based application to compute acoustic wave velocity in crystals and its magnetic corrections, SoftwareX 33 (2026) 102472.

https://doi.org/10.1016/j.softx.2025.102472 (Open access)

If you have used VelCrys, please cite it as

@article{NIEVES2026102472,
author = {P. Nieves and I. Korniienko and A. Fraile and J.M. Fernández-Díaz and R. Iglesias and D. Legut},
title = {VelCrys: Interactive web-based application to compute acoustic wave velocity in crystals and its magnetic corrections},
journal = {SoftwareX},
volume = {33},
pages = {102472},
year = {2026},
doi = {https://doi.org/10.1016/j.softx.2025.102472} }