120th General Meeting of the KCS

Type Symposium
Area Recent Progress in Electronic Structure Theory
Room No. Room 208+209+210
Time THU 14:30-:
Code PHYS1-3
Subject Electronic structures of TiO2 nanoparticles by DFT approaches
Authors JIN YONG LEE
Department of Chemistry, Sungkyunkwan University, Korea
Abstract DFT approaches have been successfully applied for many research areas in chemistry. Recently developed various functionals could give more reliable results in many different subjects, however, it is still lack of fundamental unified functional. For example, band gaps of TiO2 bulk or nanoparticles are critical for the photocatalytic activities in water splitting. For bulk TiO2, LDA and GGA functionals underestimated band gaps, and resulted incorrect description of mid gap states of oxygen vacances in reduced oxides. On the other hand, hybrid functionals, B3LYP (20% of HF) and PBE0 (PBE+25% of HF) overestimated the band gaps, and HSE (PBE0 + screening parameter) predicted oxygen vacancy defect state levels too deep in the gap. The most accurate many body approaches (GW) may overcome this band gap problem, but computationally too expensive. We optimized the HF percentage in PBE functional to obtain accurate band gap of bulk TiO2. Then, using this functional we studied the electronic structure of the ground and excited states of TiO2 nanoparticles. We will discuss on the minimum size of cluster to keep the facet in clusters and exciton binding energy of nanoparticles.
E-mail jinylee@skku.edu