where \(H = H_0 + H_1\), \(H_1\) is the external perturbed Hamiltonian operator, and E is the
eigenvalue. In order to solve the mixing coefficients \(c_0\) and\( \) \(c_1\), we multiply both sides of Eq.(1) with\(|0\rangle\) and \(|1\rangle\), and integrate the coordinate from \(-\ \infty\) to \(\infty\). Then, we can obtain