BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:"\;New Developments in Semiempirical MO Theory for Drug and Ma terials Design"\; - Professor Tim Clark\, Friedrich-Alexander-Universi tät Erlangen-Nürnberg\, Germany DTSTART:20110922T130000Z DTEND:20110922T143000Z UID:TALK32152@talks.cam.ac.uk CONTACT:Susan Begg DESCRIPTION:Semiempirical (NDDO-based\, MNDO-like) molecular orbital (MO) theory has led a life in the shadows for several decades\, probably becaus e “more respectable” techniques\, such as density-functional theory\, have become applicable to quite large molecules\, including transition-met al complexes. However\, the great strengths of semiempirical MO theory (sp eed\, scaling\, one-electron properties\, and excited states) remain. \n\n Two independent parameterizations (PM6 and AM1*) for the first-row transit ion metals are now available\, so that these elements can be treated succe ssfully. Classical dispersion potentials have been added to standard param eterizations in the same spirit as DFT-D.\n\nWe have developed a massively parallel code that brings calculations on 100\,000 atoms within reach on 1\,000 processors with high efficiency\, but also gives super-scalar perfo rmance on 8-32 processors\, for instance on dual or quad-core nodes. Simil arly\, geometry optimizations on datasets of 100\,000 drug-sized molecules and more are possible in a weekend on an eight-core node. These capabilit ies open new possibilities and applications of semiempirical MO theory.\n\ nAmong these is the use of Pulay’s UNO-CAS technique to give reliable ba nd gaps for semiconductors\, which\, combined with a newly developed direc t optimization algorithm for the UHF density matrix\, also allows calculat ions on conductors for the first time.\n\nThese developments provide a pow erful tool for materials modeling\, in particular for spectroscopic and el ectronic properties\, but also for high-quality quantitative structure-pro perty relationships without resorting to an atoms-and-bonds picture of mol ecules.\n LOCATION:Pfizer Lecture Theatre\, Dept. of Chemistry END:VEVENT END:VCALENDAR