| DATE: |
2004-12-09 11:00 - 12:00 |
| PLACE: |
4-go-kan, 2F Rinkoshitsu 1 |
| TITLE: |
PF Seminar Determination of crystal structures based on powder diffraction data |
| SPEAKER: |
Prof.L.A.Aslanov (Department of Chemistry, Moscow State University) |
| LANGUAGE: |
English |
| URL: |
http://pfwww.kek.jp/pf-seminar/ |
| ABSTRACT: |
A major advance in recent years has occurred in the determination of crystal structures ab initio from powder diffraction data. Two approaches for determination of molecular crystal structures will be discussed and compared: simulated annealing and grid search which were developed by V.V.Chernyshev in laboratory of Structural Chemistry of Moscow University in close collaboration with Prof.H.Schenk (Amsterdam). A few examples will be considered including unexpected molecular structure of 2,4-dinitro-N-phenyl-6(phenylazo)-benzamide and related compounds. Spectroscopic methods produced incorrect starting model of molecular structure for mentioned compound but grid search built a real molecular structure. It was found that solution of the crystal structure depends on grid increment and grid search is more reliable than simulated annealing. |
