Whenever you mention 4C in some sort of scientific document/publication/presentation, please cite 4C as follows:
4C: A Comprehensive Multi-Physics Simulation Framework, https://www.4c-multiphysics.org
You could use the following BibTeX entry:
@misc{4C,
author = {4C},
title = {4C: A {C}omprehensive {M}ulti-{P}hysics {S}imulation {F}ramework},
howpublished = {\url{https://www.4c-multiphysics.org}},
year = {YEAR},
note = {Accessed: DATE}
}
Note: You might need to adapt the BibTeX entry depending on the citation style.
Remember: It is good scientific practice to include the date, when you’ve visisted that website, into the citation. It’s up to you (and your advisor) to include the date, depending on the type of publication.