Global minimum search

Recent advances in experimental techniques at the nanoscale and in high throughput experimentation (HTE) provide either information with unprecedented spatiotemporal resolution or massive data. Extraction of information from such data is also an optimization problem that is often referred to as reverse engineering. Here one bypasses the question of which are the actual kinetics giving rise to the experimental structures, i.e., how do these structures form and whether they are metastable or not, and simply focuses on determining these structures from data. Therefore, forward nonequilibrium KMC simulation is not carried out. Instead, MC is merely used as an efficient global minimum search (optimization) method [note that the term reverse MC (RMC) is also often employed] to determine structures consistent with experimental data. 

Kazimirski and Buch [49] foresaw and Takeuchi [51 ] refined a different approximate but fast H-bond topology optimization which can be used as part of a global minimum search. We now describe our version of this method which we call the short topology-altering optimization . 

Fig. lObl. Afterwards, a similar global minimum search for 635 was... 

Dmparison of various methods for searching conformational space has been performed cycloheptadecane (C17H34) [Saunders et al. 1990]. The methods compared were the ematic search, random search (both Cartesian and torsional), distance geometry and ecular dynamics. The number of unique minimum energy conformations found with 1 method within 3 kcal/mol of the global minimum after 30 days of computer processing e determined (the study was performed in 1990 on what would now be considered a / slow computer). The results are shown in Table 9.1. 

For all but the smallest of molecules, a search for the global minimum may be impossible. 

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