Improved DFT Potential Energy Surfaces via Improved Densities

Density-corrected DFT is a method that cures several failures of self-consistent semilocal DFT calculations by using a more accurate density instead. A novel procedure employs the Hartree–Fock density to bonds that are more severely stretched than ever before. This substantially increases the range of accurate potential energy surfaces obtainable from semilocal DFT for many heteronuclear molecules. We show that this works for both neutral and charged molecules. We explain why and explore more difficult cases, for example, CH⁺, where density-corrected DFT results are even better than sophisticated methods like CCSD. We give a simple criterion for when DC-DFT should be more accurate than self-consistent DFT that can be applied for most cases

Simultaneous Etching and Doping by Cu-Stabilizing Agent for High-Performance Graphene-Based Transparent Electrodes

Cu etching is one of the key processes to produce large-area graphene through chemical vapor deposition (CVD), which is needed to remove Cu catalysts and transfer graphene onto target substrates for further applications. However, the Cu etching method has been much less studied compared to doping or transfer processes despite its importance in producing higher quality graphene films. The Cu etchant generally includes a strong oxidizing agent that converts metallic Cu to Cu²⁺ in a short period of time. Sometimes, the highly concentrated Cu²⁺ causes a side reaction leading to defect formation on graphene, which needs to be suppressed for higher graphene quality. Here we report that the addition of metal-chelating agents such as benzimidazole (BI) to etching solution reduces the reactivity of Cu-etching solution by forming a coordination compound between BI and Cu²⁺. The resulting graphene film prepared by Cu stabilizing agent exhibits a sheet resistance as lows as ∼200 Ohm/sq without additional doping processes. We also confirmed that such strong doping effect is stable enough to last for more than 10 months under ambient conditions due to the barrier properties of graphene covering the BI dopants, in contrast to the poor stability of graphene additionally doped by strong p-dopant such as HAuCl₄. Thus, we expect that this simultaneous doping and etching method would be very useful for simple and high-throughput production of large-area graphene electrodes with enhanced conductivity