Dear Professor,

I hope this message finds you well.

I am currently engaged in machine learning research using ChimeraX. As part of my work, I need to substitute various groups on the phosphorus atom, including methyl, tert-butyl, cyano groups, and others. However, the current substitution function does not cover many groups, so I have been manually adding them to the SEQCROW library.

At present, I am building the structures in Gaussian, which is quite cumbersome. Since I am not very familiar with ChimeraX, I am unsure whether it allows for manual molecular structure building. If such functionality is available, it would greatly assist my work.

I would greatly appreciate any guidance or suggestions you might have.

Thank you very much for your time and assistance.

Best regards,

Youcai Zhu