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Morphology of crystals; Hartman-Perdok theory; cohesive energy of crystals; ZTS crystals

The growth morphology of crystals of zinc tris(thiourea) sulphate (ZTS) is investigated experimentally, and computed using the Hartman-Perdok approach. Attachment energies of the observed habit faces are calculated for determining their relative morphological importance. A computer code is developed for carrying out these calculations. A special procedure is adopted for computing the cohesive energy of a slice of the structure parallel to any rational crystallographic plane. For estimating the cohesive energies, formal charges on the experimentally determined atomic positions in the molecules of ZTS are calculated by ab initio molecular-orbital computations, with wave functions obtained by the Hartree-Fock procedure. Fairly good agreement with the observed crystal morphology is obtained for a model of growth mechanism in which ZTS is assumed to exist in solution sa szinc tris(thiourea) ions and sulphate ions.

Sunil Verma¹ MK Singh¹ VK Wadhawan¹ CH Suresh^{1 2}

1. Laser Materials Division, Centre for Advanced Technology, Indore - 452 013, India
2. Department of Chemistry, University of Pune, Pune - 411 007, India

Published

June 2000

Manuscript received

7 January 2000

Manuscript revised

18 May 2000