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To establish the correlation between catalyst structure and its activity has been a goal constantly pursued in catalysis.To pinpoint the active site at the atomic level and thus guide the design of new catalyst is considerably challenging.[1-3] A major concern is that the structure of the catalyst is not invariant but will change under reaction conditions.It is notorious that the minority sites such as steps and defects on catalyst surfaces can be generated dynamically during the reaction and affect significantly the catalyst performance.Fundamental understandings on the structure versatility and their catalytic consequence are much needed towards unveiling the catalytic mechanism under realistic reaction conditions.The focus of the current work is on the structure preference and the catalytic consequence for metal nanoparticles under realistic reaction condition.We are interested in the metal nanoparticles of tens to hundreds atoms,which can themselves act as the catalyst and is also important as the nucleation sites in long-term catalyst operation.Here the recently-developed stochastic surface walking(SSW)global optimization method[4-5] is combined with first principles method to sample the PES of Pt particles.We show that the PES of metal particles varies significantly under different environment: not only the strength of the metal-support interaction but also the shape of the interacting field critical to the PES.