Nowadays, AlphaFold2 is the best choice for modelling proteins. And it also provides you the refined and energy minimised structure. Apart from that you can use phyre2, ROBEETA for ab initio modelling followed by energy minimisation using galaxy refine.

Dear Shilpa Sarkar,

The following data may be helpful:

GPCR-I-TASSER is a computational method designed for 3D structure prediction of G protein-coupled receptors:

https://zhanggroup.org/GPCR-I-TASSER/

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Which program is the best for ab-initio modeling of a protein? How does one use such a program?

https://www.researchgate.net/post/Which-program-is-the-best-for-ab-initio-modeling-of-a-protein-How-does-one-use-such-a-program

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BIO-GATS: A Tool for Automated GPCR Template Selection Through a Biophysical Approach for Homology Modeling

https://www.frontiersin.org/articles/10.3389/fmolb.2021.617176/full

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GPCR & Company: Databases and Servers for GPCRs and Interacting Partners

https://link.springer.com/chapter/10.1007/978-94-007-7423-0_9?error=cookies_not_supported&code=11cb81dd-d6b8-40fb-8b5f-1b6fdb485ec3

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