for a 1D free particle with initial wave function [itex]\phi(x')[/itex] square shaped(e.g. [itex]\phi(x')=1,x'\in [a,b][/itex],otherwise it vanishes),(adsbygoogle = window.adsbygoogle || []).push({});

my question is: how does it evolve with time [itex]t[/itex]?

if we deal with it in [itex]P[/itex] basis, it is easily solved, using the propagator [itex]U(t)=∫|p'><p'|e^{-\frac{ip'^2 t}{2m\hbar}}dp'[/itex];

but if we directly solve SE in [itex]X[/itex] basis, where [itex]P[/itex] must be written as [itex]-i\frac{∂}{∂x'}[/itex], the initial wavefunction is not continous, so the equation becomes improper at the ends of the interval[itex][a,b][/itex],

so why dose the SE equation seems so distinct in these 2 representations? what goes wrong in [itex]X[/itex] representation?

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Square shape wave packet spreading

**Physics Forums | Science Articles, Homework Help, Discussion**