I am not familiar with the platform you used. The mod_2f2.mod should be automatically built, because of this line in Makefile:
2F2.f90.o : ext/2F2.f90 util.o Bspline.o
$(FC) $(OPT) -c ext/2F2.f90 -o 2F2.f90.o
where 2F2.f90 defines module mod_2F2. And as can be seen in Makefile, 2F2.f90.o is prerequisite when compiling many other source code files. I didn't encounter problem in compiling Multiwfn under CentOS 6.
]]>Is there any chance that this would be fixed and a new version released?
Thank you,
Yuri (maintainer of the FreeBSD port)