Modifying the Interlayer Interaction in Layered Materials with an Intense IR Laser

We propose a transient interlayer compression in two-dimensional compound materials by using an intense IR laser resonant with the out-of-plane optical phonon mode (${A}_{2\mathrm{u}}$ mode). As a test case, we studied bilayer hexagonal boron nitride ($h$-BN), which is one of the compound layered materials. Excited state molecular dynamics calculations using time-dependent density functional theory show an 11.3% transient interlayer contraction of $h$-BN due to an interlayer dipole-dipole attraction of the laser-pumped ${A}_{2\mathrm{u}}$ mode. These results are applicable to other layered compound materials. Such layered materials are a good material for nanospace chemistry, e.g., intercalating molecules and acting with them, and IR irradiation to contract the interlayer distance could provide a new route for chemical reactions under pressure. The duration of the contraction is at least 1 ps in the current simulation, which is observable by high-speed electron-beam diffraction measurements.