A particle is in a box of length L on x-axis. 0<x<L. What is the first order shift due to V(x) of the wavefunction?
The Attempt at a Solution
I'm super confused because the shift in the energy is usually determined by a sum, not an integral. Unless I calculate En(1) by taking;
=V * integral(2/Lcos2(nxpi/L)dx) with limits 0 to L
Is this the correct way to do this one? I didn't include k very well unless I put it in for V at the end...