Dear all, I figured out how to compile charmm on ubuntu 18.04 system. My error above came from fftw. After i installed libfftw3-3 and libfftw3-dev, I can run configure without any problem, then can compile charmm. Intel compilors are not necessary for the compiling. Gfortran and Gcc compilors are good enough.

I only have one question. Right now, after typing sudo make install command, i can install charmm. But I do not know if it is the xxlarge size. I am wondering how to control that.