ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The previously formulated new approach to the structure analysis of a crystal based on the profound analogy between the problem of determination of thermodynamic equilibrium in statistical mechanics and the optimization problem for a function of many variables [Khachaturyan, Semenovskaya & Vainshtein (1979). Soy. Phys. Crystallogr. 24, 519-524; (1981). Acta Cryst. A37, 742-754] is developed. In this approach, a crystal structure is determined by the equilibrium low-temperature state of a model non-ideal gas composed of the atoms within a crystal unit cell, the unit cell and the R factor being regarded as a vessel and an interatomic interaction Hamiltonian, respectively. In contrast to the above cited papers, the low-temperature equilibrium state is found by means of the Monte Carlo sampling scheme usually utilized in statistical mechanics applications. The main advantage of such a treatment is that the system reaches the equilibrium state avoiding all 'traps', metastable (local) minima of the free energy, and thus provides automatic determination of the crystal structure. The method is successfully tested on the known L-proline structure containing 32 non-hydrogen atoms per unit cell. The proposed statistical mechanics approach can also be applied with minor modifications to optimization problems in the multi-dimensional space of many variables.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0108767385000563
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