Real space simulation for high-resolution atomic force microscopy of defects in monolayer h-BN

High-resolution atomic force microscopy (HR-AFM) with a CO-functionalized tip allows for atomically resolved imaging of point defects in two-dimensional materials. We employ real-space density functional theory simulations to examine HR-AFM imaging of a representative point defect in monolayer hexagonal boron nitride (h-BN): a carbon substitution of boron and an adjacent nitrogen vacancy (C_BV_N). We introduce an iterative tilt correction method that is computationally inexpensive and addresses the common overestimation of lateral tip displacement in AFM simulations at small tip-sample distances. The simulated image of the singlet (¹A₁) state with out-of-plane displacements exhibits a bright spot that shifts with tip height due to orbital tilts, highlighting the electronic orbital contribution to AFM images. In contrast, the planar triplet (³B₂) state produces a distinct image without this shift of the bright spot. These results demonstrate the ability of HR-AFM to reveal the interplay between structural geometry and electronic state configuration at the atomic scale.