Morales-García Ángel, Valero Rosendo, Illas Francesc
Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTUB), Universitat de Barcelona , c/Martí i Franqués 1, 08028 Barcelona, Spain.
J Chem Theory Comput. 2017 Aug 8;13(8):3746-3753. doi: 10.1021/acs.jctc.7b00308. Epub 2017 Jul 5.
Using a relativistic all-electron description and numerical atomic-centered orbital basis set, the performance of the GW method on the electronic band gap of (TiO) nanoparticles (n = 1-20) is investigated. Results are presented for GW on top of hybrid (PBE0 and a modified version with 12.5% of Fock exchange) functionals. The underestimation of the electronic band gap from Kohn-Sham orbital energies is corrected by the quasiparticle energies from the GW method, which are consistent with the variational ΔSCF approach. A clear correlation between both methods exists regardless of the hybrid functional employed. In addition, the vertical ionization potential and electron affinity from quasiparticle energies show a systematic correlation with the ΔSCF calculated values. On the other hand, the shape of the nanoparticles promotes some deviations on the electronic band gap. In conclusion, this study shows the following: (i) A systematic correlation exists between band gaps, ionization potentials, and electron affinities of TiO nanoparticles as predicted from variational ΔSCF and GW methods. (ii) The GW approach can be successfully used to study the electronic band gap of realistic size nanoparticles at an affordable computational cost with a ΔSCF accuracy giving results that are directly related with those from photoemission spectroscopy. (iii) The quasiparticle energies are explicitly required to shed light on the photocatalytic properties of TiO. (iv) The GW approach emerges as an accurate method to investigate the photocatalytic properties of both nanoparticles and extended semiconductors.
采用相对论全电子描述和数值原子中心轨道基组，研究了GW方法对（TiO）纳米颗粒（n = 1 - 20）电子带隙的性能。给出了基于杂化（PBE0和具有12.5%福克交换的修正版本）泛函之上的GW结果。Kohn-Sham轨道能量对电子带隙的低估通过GW方法的准粒子能量得到修正，该能量与变分ΔSCF方法一致。无论采用何种杂化泛函，两种方法之间都存在明显的相关性。此外，准粒子能量的垂直电离势和电子亲和势与ΔSCF计算值呈现出系统的相关性。另一方面，纳米颗粒的形状会导致电子带隙出现一些偏差。总之，本研究表明：（i）变分ΔSCF和GW方法预测的TiO纳米颗粒的带隙、电离势和电子亲和势之间存在系统的相关性。（ii）GW方法能够以可承受的计算成本成功用于研究实际尺寸纳米颗粒的电子带隙，其精度与ΔSCF相当，得到的结果与光电子能谱直接相关。（iii）明确需要准粒子能量来阐明TiO的光催化性质。（iv）GW方法成为研究纳米颗粒和扩展半导体光催化性质的一种精确方法。
