Quantifying the distances between atomic configurations

Dr. Ali Sadeghidr-sadeghi

Tehran ,Shahid Beheshti University

Tuesday 13/11/94, 15 – 16

Ibn Al-haytham Hall, Physics Department



 The arrangement of the atoms within the unitcell of a crystalline structure or an atomic cluster determines mechanical, electronic and magnetic properties of that structure.  The atomic arrangement may be determined experimentally (e.g. by XRD techniques) or predicted theoretically (e.g. by ab initio calculations) and is given as a list of real space atomic coordinates along with the lattice vectors. Quantifying the similarity or dissimilarity between two configurations, as is highly demanded in various fields of research including structure prediction of nanostructures, biophysics, drug discovery, etc., is based on comparing such arrays of numbers. A reliable comparison should however be independent of the rigid translation and orientation of the configurations,  and more importantly, of the order of the atoms in the array. Some computational techniques to overcome the complexities rised from such invariance requirements  will be explored in this talk, and thier application to various nanostructres will also be addressed.