# Phase shift for Scattering in radial potentials

given a radial potential in 3 dimension and its Schroedinguer equation

$-D^{2}U(r) + \frac{l(l+1)}{r^{2}}+V(r)$ here D means derivative with respect to 'r'

then if we apply quantum scattering how can we calculate the PHASE SHIFT ?? $\delta$ , for a general potential ?? .. for example with the condition $V(r) \to \infty$ as $r\to \infty$

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–  Qmechanic Nov 17 '11 at 15:19
Do you mean V(r) goes to zero at large r? If V(r) goes to infinity, there are no scattering states, the motion is bound. Also V(r) needs to go to zero fast enough for the phase shift to approach a limit, generally this means V(r) goes to zero faster than 1/r. Electrostatic potential scattering with a 1/r potential has a logarithmically diverging phase shift, making the S-matrix undefined without a small photon mass. This is a form of infrared divergence. –  Ron Maimon Nov 17 '11 at 15:20
thanks RON i forgot :) , yes the potential is $V(r) \to 0$ as $r\to \infty$, whenever you say SCATTERING STATES you are referring to states with CONTINUUM energy in the form $k^{2}+a^{2}$ here 'k' is the wave number and 'a' is a constant :) –  Jose Javier Garcia Nov 17 '11 at 15:50

For a general potential $V(r)$ you can use the variable-phase method.