Dear Elsaid Mohamed, is it a new polymer ? If not it is wise to check literature for possible hints. There are many models and approaches, where Rg and Rh (hydrodynamics radius) are are in competetive way to represent the real dimensions. Please have a look at the following documents. My Regards

https://doi.org/10.1016/j.physleta.2019.125860

https://iopscience.iop.org/article/10.1088/0305-4470/21/22/022/meta

https://doi.org/10.1021/ma00030a017

https://www.researchgate.net/publication/350484519_On_gyration_radius_distributions_of_star-like_macromolecules

Hi, I could not have downloaded the attached, but I found another paper that explains it:

Rg^2=(mi*|ri^2| +mj|rj^2|...)/MT

where mi is the mass of the atom I and ri is the distance from the center of mass to the atom i.

MT is the total mass.

Is that right?

You don't specified the reference of the equation. There are many deivations for RG. Is it for star polymers? Following is the DOI of the paper attached to my previous contribution. Good Luck in your work

https://doi.org/10.1016/0032-3861(92)90337-V

Thanks a lot. Here is the paper I mentioned.

Note I considered dendrimer G4 as a star-like polymer.

https://www.researchgate.net/publication/223636130

I think there are some pecularities between the two architectures. The following documents deals with simulation and comparison between them.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9269100/

https://www.nature.com/articles/pj2010109

https://doi.org/10.1016/S0079-6700(00)00011-3

Dear Elsaid Mohamed

You need to use the Small-Angle X-Ray Scattering (SAXS) technique to calculate the Radius of gyration by the plotting the intensity versus the scattering vector q .

Wishing you all the best

Thanks, I did finish the project, and uploaded it to GitHub. If you are interested you can find the report in "ReportComputationBoltornG4.pdf"

Wish me good luck finding a suitable PhD position!

https://github.com/elkhot/Boltorn-4G_MD