Surface electronic structure calculations using the MBJLDA potential: application to Si(111)2 × 1.

The Si(111)2 × 1 surface has been widely studied via a range of different experimental and theoretical techniques, and found to adopt a π-bonded chain configuration. To determine an accurate electronic structure for this system, however, it has been found necessary to use sophisticated and very computationally expensive methods such as GW or hybrid functionals. In this article, we show that the MBJLDA approach, originally proposed by Tran and Blaha for bulk materials (Tran and Blaha, Phys. Rev. Lett. 2009, 102, 226401), yields results which are comparable to GW, and generally superior to those obtained from hybrid functional density functional theory calculations. The MBJLDA method is also substantially more computationally efficient. A procedure and justification for the application of the MBJLDA approach to surfaces in general is also provided.

An improved density functional theory description of the Ge(100)c(4×2) surface using the MBJLDA xc potential and spin-orbit interactions.

The MBJLDA xc potential (modified Becke-Johnson exchange potential with local density approximation correlation) proposed by Tran and Blaha has been designed and shown to significantly improve the description of the fundamental energy gaps of a wide range of bulk materials. Recently we reported that combining this MBJLDA xc potential with spin-orbit interactions and local density approximation pseudopotentials within the plane wave density functional method led to results for bulk germanium that were at least as accurate as those obtained from far more sophisticated and computationally expensive methods such as the GW method. Here we demonstrate that the application of this approach to the Ge(100)c(4×2) surface yields results that are in excellent agreement with the available experimental data.