it is a bit tricky to compile this code because of the module dependencies. The following attachment has suitable Makefiles for gfortran. It should be fairly simple to adapt it for other compilers.
Makefiles.tar.gz

Peter

In the main program, results_raw.dat is written using logical unit 6 (stdout). It is than read using logical unit 15. You may get away with this, but it is strictly incorrect to have the same file open in two logical units. However, it fails in practice because stdout is still open, and if it is block buffered, the data hasn't been written to the file when calc() runs. (This must have worked at some point; the Fortran implementation must have used line buffering for stdout even after the unit was reopened onto a file.)

The attached patch changes the logical unit from 6 to 8, and closes it (which flushes the contents) before calc() runs and opens the file.

modal_model-unit.patch.txt

Peter