Editing GAUSSIAN (section)

=== ABOUT SENDING CALCULATIONS :===
* '''Checkpoints''': They are big files which contain information such as the wave function or the geometry of finished calculations. They can not be edited with vi or nedit... (as they are written in binary) but the information they contain can be read by Gaussian. Although they might be very useful, to store them is not recommended if we are not sure about their utility. 

In kimik/kimik2, when the calculation finishes they are saved in the same directory as the output. For practical reasons while the calculation is running the checkpoint file should be saved in the Scratch. The submision script qs adds the lines 

 %chk=/scratch/filename.chk 
 %nprocs=XX  (XX corresponds the ''type'' of node (4,8 or 12) you requested in qs

* '''Memory''': The qs script does not add a line to specify memory usage, which must be done manually with the "%Mem=" command. As a rule you should specify no more than 85% of a node's memory capacity to allow for normal OS operations, like disk writing and network access, otherwise you will start using swap space and slow down the calculation drastically (especially in frequency calculations)

* '''--link1--'''; you can link calculations by writing the inputs one after the other and adding '''--link1--''' between them (one blank line before link1 and no blank line after). With this and the keywords geom=(checkpoint), guess=(read)... you could save time when doing solvent calculations or other. The outputs will be written in a single file.