(E e -E g ), in addition to considering the light-matter coupling in terms of 0 i |0 j • V ij , the couplings 0 i |n j • V ij also become relevant because E e -E g ≈ E e -E g + n j hω c . Under this circumstance, the effect on the ground polariton state becomes frequency dependence, such as those vibrational strong coupling (VSC) case when hω c