A new variational method for calculating eigen energy in various quantum wells on the basis of effective well width

In this paper we would like to propose a simple and novel method. This is a variational method in which the effective well width is introduced as a variational parameter. Through a simple calculation, an approximate value of the eigen energy very close to the accurate value can be obtained for the finite rectangular quantum well (RQW) as an example. Mass-independent nature of the Stark shift due to the quantum confined Stark effect in the parabolic QW and the QW with mass-dependent width is also well explained on the basis of this new method