| Abstract
| - Using hybrid Monte Carlo molecular simulations, we study crystallization from the melt of softly repulsivespheres interacting through an inverse power law potential. We work at fixed supercooling (i.e., at a temperature25% below the melting temperature) and consider three systems, defined by different values for the inversepower exponent n: n = 5, n = 6.67, and n = 10. Modifying the value of n allows us to study the onset ofcrystallization in the domain of stability of the body-centered cubic (bcc) phase (n = 5 and n = 6.67) and inthe domain of stability of the face-centered cubic (fcc) phase (n = 10). We show that, for the three systems,polymorph selection does not take place during crystal nucleation since the structure of the critical nucleiobtained for the three systems is not well defined. However, our results demonstrate that polymorph selectiontakes place during the growth step since growth proceeds either into the stable bcc phase for the two smallervalues of n (n = 5 and n = 6.67) or into the stable fcc phase for the larger value of n (n = 10). We also showthat we did not achieve complete control of polymorphism for n = 10. The growth step gives rise to eitherslowly growing crystallites composed of two blocks of different structures (the stable fcc form and themetastable bcc form) or rapidly growing crystallites of the metastable bcc form.
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