Is the uniform electron gas limit important for small Ag clusters? Assessment of different density functionals for Ag(n) (n < or = 4).
Twenty-three density functional theory (DFT) methods, including the second- and the third-generation functionals, are tested in conjunction with two basis sets (LANL2DZ and SDD) for studying the properties of neutral and ionic silver clusters. We find that DFT methods incorporating the uniform electron gas limit in the correlation functional, namely, those with Perdew's correlation functionals (PW91, PBE, P86, and TPSS), Becke's B95, and the Van Voorhis-Scuseria functional VSXC, generally perform better than the other group of functionals, e.g., those incorporating the LYP correlation functional and variations of the B97 functional. Strikingly, these two groups of functionals can produce qualitatively different results for the Ag3 and Ag4 clusters. The energetic properties and vibrational frequencies of Ag(n) are also evaluated by the different functionals. The present study shows that the choice of DFT methods for heavy metals may be critical. It is found that the exact-exchange-incorporated PBE functional (PBE1PBE) is among the best for predicting the range of properties.
Zhao
Shuang
S
Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Center for Theoretical Chemical Physics, Fudan University, Shanghai 200433, People's Republic of China.
Li
Zhen-Hua
ZH
Wang
Wen-Ning
WN
Liu
Zhi-Pan
ZP
Fan
Kang-Nian
KN
Xie
Yaoming
Y
Schaefer
Henry F
HF