Is it possible at present quantum chemistry to predict minimum geometry and orientation of cluster of organic molecules? Is possible can I use gaussian? Amber? and what keywords to be used.
Why not? MP2 method with aug-cc-pvXZ basis set can be heplful as a first approach.
dear woon
yea, one of the most popular facility in gaussian program is the prediction of minimum of structures. u can use the opt keyword for it and as Alexander said MP2 with foresaid basis set
This is a very tricky thing to get right. If you have hydrogen bonds then the results will probably be much better. I would start with DFT to get a rough starting structure. Maybe with B3lyp or APFD at 6-31G* depending upon the system size. MP2 will take a really long time. Also solvent effects can be a problem any method.