## Abstract

Using first-principles calculations with ultrasoft pseudopotential formalism and the generalized gradient approximation for the exchange-correlation functional, we study the stability of Mo_{n}S _{m} (n = 1-6 and m ranging from n to 3n) clusters and obtain the optimal stoichiometry for each n corresponding to the magic cluster. It is found that in this size range, the lowest-energy structures favor a core of metal atoms, which is covered by sulfur. In particular, we observe that for Mo _{6}S_{14} isolated clusters, a 3D structure is significantly lower in energy as compared to platelet structures found recently on Au (111) surface. The composition ratio between S and Mo in the magic clusters is less than 2 for n = 3 and greater than 2 for n < 3. The structural stability of the magic clusters arises from the optimization of the Mo-Mo and Mo-S bonding as well as the symmetry of the cluster. Addition of a terminal sulfur in a magic cluster generally lowers its binding energy. The presence of partially occupied d-orbitals in Mo atoms contributes to Mo-Mo bonding and for higher S concentration it leads to sulfur-sulfur bond formation. The variation in energy due to a change in the sulfur composition suggests that sulfurization of the magic clusters is generally more favorable than desulfurization.

Original language | English |
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Pages (from-to) | 2778-2782 |

Number of pages | 5 |

Journal | Journal of Physical Chemistry A |

Volume | 111 |

Issue number | 14 |

DOIs | |

Publication status | Published - 2007 Apr 12 |

## ASJC Scopus subject areas

- Physical and Theoretical Chemistry