Studies Of The Precise Exchange-correlation Functional Of Noble Metals

In the thesis,we studied the the precise exchange-correlation functional of noble metals,using the density funcitional theory.The conventional density functional theory calculations heavily bias planar structures for gold clusters,failing in predicting the structural transition from planar to three-dimensional geometries for experimentally detected gold species.With the purpose to find an appropriate method for the precious materials,we carried out careful DFT calculations by the different functionals.Inspired by previous progress in accurately calculating defect energy for coinage metals,we have studied the nonlocal effects for gold clusters.Though the hybrid functional could well treat gold bulk,it still can not well describe gold cluster.By including the dispersive interaction into nonlocal density functional calculations,our calculations can give accurate vacancy formation energy for gold bulk.Based on the PBE exchange and the correlation energy,correct structural transition also can be decribed.The transition is found to happen at Au_{1 2} for gold anions and Au₈ for gold cations,agreeing very well with the experimental results.For neutral gold clusters,our careful discussion suggests it to occur at Au₁₀,calling for verification in experiment.We also studied the effects from the different functionals for the perious materials,by using the PBE,PEBsol,TPSS and RTPSS combined with the van der Waals interactions.We calculated the structural properties of clusters with different electrical states.We can get the same results with TSD-PBE,by using RTPSS-D3method,which shows that the RTPSS-D3 method also be an appropriate method to describe the proprious materials.These studies show the importance of nonlocal effects for studying gold clusters and also shed light on the theory development on dealing with nonlocal contributions in density functional theory calculations.