A benchmark method for global optimization problems in structure determination from powder diffraction data

作者：Shankland Kenneth^*; Markvardsen Anders J; Rowlatt Christopher; Shankland Norman; David William I F

来源：Journal of Applied Crystallography, 2010, 43: 401-406.

DOI：10.1107/S0021889810008113

Quasi-Newton-Raphson minimization and conjugate gradient minimization have been used to solve the crystal structures of famotidine form B and capsaicin from X-ray powder diffraction data and characterize the chi(2) agreement surfaces. One million quasi-Newton-Raphson minimizations found the famotidine global minimum with a frequency of ca 1 in 5000 and the capsaicin global minimum with a frequency of ca 1 in 10 000. These results, which are corroborated by conjugate gradient minimization, demonstrate the existence of numerous pathways from some of the highest points on these chi(2) agreement surfaces to the respective global minima, which are passable using only downhill moves. This important observation has significant ramifications for the development of improved structure determination algorithms.

• 出版日期2010-6