explicitly correlated calculations (dependence on 1/r;Section 5.4.1). MOLPRO
does not implement the CASPT2N code as in MOLCAS, but “the multi-reference
perturbation theories in MOLPRO and MOLCAS are quite similar, and the
CASPT2N Hamiltonian can be reproduced in MOLPRO”.^3 Other programs that
implement methods designed to accomplish “post-CAS” energy calculations are
GAUSSIAN and GAMESS.
MOPACThe name means Molecular Orbital Package, but is said to have been
inspired by this geographical oddity: “The original program was written in Austin,
Texas. One of the roads in Austin is unusual in that the Missouri–Pacific railway
runs down the middle of the road. Since this railway was called the MO-PAC, when
names for the program were being considered, MOPAC was an obvious contender”
(see website).
http://openmopac.net/manual/index_troubleshooting.html
A semiempirical suite of programs. SeeChapter 6.
9.3.1.6 P
PCModelMarketed by Serena Software
http://www.serenasoft.com/
Primarily molecular mechanics, but now includes semiempirical. Can serve as
a GUI for ab initio and DFT program suites.
9.3.1.7 Q
Q-ChemQuick chemistry
http://www.q-chem.com/
“The first commercially available quantum chemistry program capable of
analyzing large structures in practical amounts of time.” For ab initio (including
high-level correlated methods) and DFT. Q-Chem is available for PCs running
under LINUX or Windows, for UNIX workstations, and for supercomputers.
9.3.1.8 S
Simple Huckel Method programs€
The simple H€uckel method, SHM (Sections 4.3.4–4.3.7):
This remains important for heuristic and pedagogic reasons, and even researchers
can find it useful. Despite what some think, it “is immensely useful as a model,
today...Because it is the model which preserves the ultimate physics, that of nodes
(^3) Personal communication, Professor E. V. Patterson, Division of Science, Truman State University,
Kirksville, MO, 2005 March 7.
580 9 Selected Literature Highlights, Books, Websites, Software and Hardware