cd /path/to/LAMMPS
tar -xvf lammps-5Jun19.tar.gz
cd lammps-5Jun2019
cd src
vi MAKE/OPTIONS/Makefile.g++_openmpi
FFT_INC = -DFFT_FFTW -I/path/to/FFTW/include FFT_PATH = -L/path/to/FFTW/lib FFT_LIB = -lfftw3
make yes-std make no-lib make -j 96 g++_openmpi