Treffer: A symmetry-oriented crystal structure prediction method for crystals with rigid bodies.

We have developed an efficient crystal structure prediction (CSP) method for desired chemical compositions, specifically suited for compounds featuring recurring molecules or rigid bodies. We applied this method to two metal chalcogenides: Li <subscript>3</subscript> PS <subscript>4</subscript> and Na <subscript>6</subscript> Ge <subscript>2</subscript> Se <subscript>6</subscript> , treating PS <subscript>4</subscript> as a tetrahedral rigid body and Ge <subscript>2</subscript> Se <subscript>6</subscript> as an ethane-like dimer rigid body. Initial trials not only identified the experimentally observed structures of these compounds but also uncovered several novel phases, including a new stannite-type Li <subscript>3</subscript> PS <subscript>4</subscript> structure and a potential stable structure for Na <subscript>6</subscript> Ge <subscript>2</subscript> Se <subscript>6</subscript> that exhibits significantly lower energy than the observed phase, as evaluated by density functional theory calculations. We compared our results with those obtained using USPEX, a popular CSP package leveraging genetic algorithms. Both methods predicted the same lowest energy structures in both compounds. However, our method demonstrated better performance in predicting metastable structures. The method is implemented with Python code which is available athttps://github.com/ColdSnaap/sgrcsp.git.
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