Here is my version of how I got NWchem to compile and run on Windows, based on the information I found in the documentation (
http://nwchemgit.github.io/index.php/Compiling_NWChem#How-to:_Windows_Platforms) and these tips (
http://nwchemgit.github.io/Special_AWCforum/sp/id5124).
Suggested process to compile and run NWchem on Windows 8.1
1. Download NWchem from
http://nwchemgit.github.io/index.php/Download
2. Download MinGW from
http://sourceforge.net/projects/mingw/files/ . Install the Basic Setup, and from All Packages, install pthreads-w32 as well as MSYS.
3. Download and install MPICH2 from
http://www.mpich.org/static/tarballs/1.4.1p1/mpich2-1.4.1p1-win-ia32.msi .
4. Assuming your MinGW installation is in the C drive, go to C:/MinGW/msys/1.0 and open msys.bat. The first time you open this application, it will create a folder C:/MinGW/msys/1.0/home/<user_name>. Unpack the NWchem download inside this folder. If necessary, shorten the name of the NWchem folder to nwchem-6.6.
5. Cut and paste the MPICH2 folder also inside the folder C:/MinGW/msys/1.0/home/<user_name>.
6. Inside the msys console, enter the following command to add the path of MinGW to the PATH environment variable:
export PATH=/c/MinGW/bin:$PATH
7. Inside the msys console, enter the following commands
export NWCHEM_TOP=~/nwchem-6.6
export NWCHEM_TARGET=LINUX
export USE_MPI=yes
export MPI_LOC=~/MPICH2
export MPI_INCLUDE=$MPI_LOC/include
export MPI_LIB=$MPI_LOC/lib
export LIBMPI="-lfmpich2g -lmpi"
export NWCHEM_MODULES=all
export DEPEND_CC=gcc
export USE_INTERNALBLAS=y
cd $NWCHEM_TOP/src
make nwchem_config
make FC=gfortran DEPEND_CC=gcc