Did you succeed in porting the code? It would not be easy according to my experience with PRIMA. I would be happy to learn if you have a GitHub repo of it. Thanks.
Yes, at least the parts that my research group used regularly. I ported them to Rust, though, not modern Fortran. They're also pretty specific to computational chemistry, rather than general packages like PRIMA, but I'll link them here in case you're curious anyway. I was also still learning Rust and followed the original Fortran API and naming scheme where possible, so this code could use a refactor too! But at least there are no gotos.
Yes, Brentward1 was indee quoting me (author of PRIMA) in his second paragraph. However, I was asking about the code he tried to port during his graduate study mentioned in his first one.
https://github.com/ntBre/anpass - ordinary least squares fitting https://github.com/ntBre/intder - internal coordinate transformations https://github.com/ntBre/spectro - vibrational perturbation theory
PRIMA looks very interesting, by the way. I may see if I can get some use out of it in my research!