Analytic approximation for eigenvalues of a class of PT-symmetric Hamiltonians

An analytical approximation for the eigenvalues of PT-symmetric Hamiltonian H = -d(2)/dx(2) - (ix) (is an element of+2), is an element of > -1 is developed via simple basis sets of harmonic-oscillator wave functions with variable frequencies and equilibrium positions. We demonstrate that our approximation provides high accuracy for any given energy level for all values of is an element of > -1.