Application of Screened Hybrid Density Functional Theory to Ammonia Decomposition on Silicon

Screened hybrid exchange-correlation (XC) density functionals incorporating short-range exact exchange aid application of hybrid density functional theory to solids and surfaces. We explore screened hybrid XC functionals for a prototypical surface reaction, namely, adsorption and dissociation of ammonia on silicon. Screened hybrids are found to improve upon standard semilocal functionals for the dissociation barrier on Si9H12, reproducing accurate complete basis set extrapolated CCSD­(T) results. Similar trends are found for realistic periodic Si(100)-2 × 2 surfaces. Screened hybrids also better reproduce experimental results for the relative barriers to different dissociation pathways. While the tested hybrid functionals tend to overestimate molecular adsorption energies, their good performance for kinetics motivates further exploration of screened exchange in surface chemistry.

引入短程精确交换的经筛选杂化交换关联（exchange-correlation, XC）密度泛函，可助力将杂化密度泛函理论应用于固体与表面体系。本研究针对一类典型表面反应——氨在硅表面的吸附与解离过程，探究了经筛选杂化XC泛函的计算表现。结果表明，对于Si₉H₁₂团簇的解离能垒，经筛选杂化泛函的性能优于标准半局域泛函，可复现完备基组外推的CCSD(T)高精度计算结果。在实际的周期性Si(100)-2×2表面体系中，同样观测到了一致的性能趋势。此外，该类泛函对于不同解离路径的相对能垒，也能更精准地复现实验结果。尽管所测试的杂化泛函往往会高估分子吸附能，但其在动力学模拟上的优异表现，仍为在表面化学领域进一步探索经筛选交换泛函提供了有力支撑。