Benchmark of DFT Functionals for the Interlayer Binding Energy of Bulk CrI3: A fixed-node quantum Monte Carlo study

Significant attention has been focused on CrI₃ since long range magnetic ordering in two-dimensional materials was first discovered in a-few-layered system. Theoretically, CrI₃ has been studied mainly using density functional theory (DFT). However, it is still under debate which functional is the most accurate. Therefore, we benchmarked several DFT functionals targeting the interlayer binding energy of bulk CrI₃. In absence of experimental data, we obtained reference values using the fixed-node quantum Monte Carlo (FNDMC), which is one of the most accurate ab initio methods for periodic systems. Comparisons of the interlayer binding energy and distance obtained with optB88-vdW, optB86b-vdW and other functionals with predicted values obtained with FNDMC will be presented.