Introduction+to+Orca

Super note: Orca uses GAMESS-US style basis sets from EMSL BSE.

Testing Orca for best general input for initial optimization -> final optimization -> CCSD(T) binding energy procedure. Structures are initially drawn in Spartan and optimized usually to EDF2/6-31G(d) or the MP2 equivalent.

Below... RI-MP2/aug-TZVPP optimization with slightly better than Gaussian09 'opt=tight' criteria. The super low energy tolerance ensures other properties converge. However, the energy itself may not reach this tolerance. code ! RHF MP2 aug-tzvpp aug-tzvpp/c TightSCF Opt %pal nprocs 2 end %scf scfmode conventional; maxdisk 20000; maxintmem 1000 end %mp2 ri true; MaxCore 2500 end %geom MaxIter 100 TolE   1.e-8 TolRMSG 1.e-5 TolRMSD 4.e-5 TolMaxG 1.e-5 TolMaxD 6.e-5 NResetHess 10 # rebuilds model Hessian frequently end H                  -0.776621231     0.000000000     0.952513902 O                   0.000000000     0.000000000     0.363048271 H                   0.776621231     0.000000000     0.952513902 Li                  0.000000000     0.000000000    -1.503864003
 * 1) MP2 optimization part (1/2)
 * 1) MP2 optimization part (1/2)
 * xyz 1 1

code