Please note: The FAQ pages at the HPCVL website are continuously being revised. Some pages might pertain to an older configuration of the system. Please let us know if you encounter problems or inaccuracies, and we will correct the entries.
Before you can access NWChem, you need to read our license agreement and sign a statement that you have done so and will abide by it. See the last section for details.
Like other electronic-structure programs, NWChem is run by supplying an input file that defines the system on which to perform a calculation (usually a molecule, or a group of molecules), and the method to use (i.e., the level of calculation, such as "Hartree-Fock", the basis set, and other details of the computation).
The variety of possible calculations is great, and so is the complexity of systems. It is impossible for us here to explain the format that a NWChem input file needs to have. This is explained in the User's Manual which is available for download in pdf and postscript format.
We provide a simple sample input file which should be given the file extension .nw. This extension may then be omitted when calling the program. NWChem creates typically a whole array of output files that are documented in the User's Manual. A general log is displayed on the console, and may be saved in a file by redirecting the standard output:
nwchem sample > sample.log
Where we assume that your input file is called sample.nw and you want to save the log to a file sample.log.
Note that this is just the basic syntax of the program call. In practise you will use a parallel environment to execute the program (see next section). In fact, attempts to execute NWChem by just typing the above line will fail.