Story of My Struggle with Computational Chemistry Freeware Package PC-GAMESS

Most chemistry-computation packages originating free of cost from the dreaded Linux-type operating systems are what should be called user-hostile (the exact opposite of the concept of being user-friendly), and I should have known that PC-GAMESS (let's call it PCG here) is unlikely to be an exception. But being a novice then, I hardly knew what extent of a struggle was in store for me when I proceeded to download PCG! I obviously have nothing other than pure gratitude to its brilliant and magnanimous developers who have over the years provided various varieties of this great package to any desirous homo sapiens just free of cost, but rather would also like to place here a few hints to any potential fellow-users.

The downloaded package was in a zip-file which could be de-coded via two password-sets, one of which required even writing an e-mail to Prof. A. Granovsky, the developer of this greatly useful package. The real struggle, however, began after that. Extracting, I got two files gamess.exe and fastdiag.dll along with three folders Docs, Readme and Samples. Wondering where to keep those, I created the folder c:\pcgamess in my (c:) hard drive, and moved all these extraction-created files & folders into it. With my third-millennium Windows ideas (which I now know are nearly useless about such packages originating in the 1980s and early 1990s), I then double-clicked at gamess.exe, but to my surprise nothing seemed to happen! What to do? I opened the Docs subfolder and double-clicked in the Input.doc, Intro.doc and Refs.doc, but found nothing about simply how to run PCG. However, I noted that the first two files seem to have very useful info (about the input-file specifications) after I would be able to run PCG; and that the .doc extension for these three files leading to invitations to Microsoft Word is uncalled for, as these three files are simply text files. So, I renamed their extensions, converting their names to Input.txt, Intro.txt and Refs.txt : they now opens in a more pleasing and extremely faster way. Next, I investigated the Readme subfolder, and found files named as readme.commandline, readme.cube, readme.p4 etc. Clearly, the file extensions are very odd and unduly different, and double-clicking them doesn't lead to direct display of their simple text contents. So, I renamed them as readme.commandline.txt, readme.cube.txt, readme.p4.txt etc. (converting each of their extensions to simply .txt). Now I had only to double-click at readme.commandline.txt to locate the following gem of a information therein:
"All PC GAMESS binaries v. 6.4 support the following command line options: gamess [-i <inputfilename>] [-o <outputfilename>]".

Oh, that's all the trick! The input-file examples were there in the Samples subfolder, starting from the simplest example in Exam01.inp. I double-clicked that file, and advised Windows to open such .inp files by Notepad, choosing Notepad from a list of programs. That input file got opened, showing its contents. So, I wondered, let me copy Exam01.inp up, to the c:\pcgamess folder and then open the MS-DOS Prompt (this almost-extinct creature gloriously thriving in my adolescent days is also called the Command Prompt, and is still available from the Programs-Accessories sub-menu of the Start Menu), enter cd c:\pcgamess just therein, and then enter gamess -i Exam01.inp -o Output.txt in the C:\pcgamess> command prompt. Wow, a black screen remained for a few seconds signifying some work going on behind my eyes, and then a big Output.txt file got created with the resulting calculations stored within it! What a pleasant surprise, I could finally work with PCG!!

I then decided I must make all these simpler for my fellow human beings, and so created a batch file DClkPCGM.bat that included written within it the command gamess -i Work2Do.inp -o Output.txt, then created a link (shortcut) file named DblClk to Run PCGAMESS that pointed to this batch file (i.e., DClkPCGM.bat) kept within C:\PCGAMESS (i.e., the PC-GAMESS working folder). Within the batch file, the (above-mentioned) central working command is preceded by a nerve-soothing message Input is Work2do.inp; Output is Output.txt and Punch; Please wait!. I then built a PCGAMESS input file named Work2Do.inp dealing with the HF 6-31G geometry-optimization calculation on benzene molecule, while making its upper contents quite explanatory by introducing quite a few explanatory comment lines. (To avoid any undesirable double-click on the files gamess.exe, FastDiag.dll and DClkPCGM.bat, I prefer to keep these three as hidden files.) Now, to run PC-GAMESS on the molecule specified in Work2Do.inp, a double-click should be made only on DblClk to Run PCGAMESS after we made Work2Do.inp ready (and protected the older contents of Output.txt & Punch somewhere else).

Hope the win-zipped set comprising the said batch file, the said link file and the said input file kept freely available on the web as DblClkPCGAMESS: The Tiny Kit for Running PC-GAMESS would help 3rd-millenium people like me to avoid the teething troubles that I went through!

-- Rituraj Kalita