Solution to the 1D Free Schrodinger Equation

jeudi 3 avril 2014

So starting from the time dependent schrodinger equation I perform separation of variables and obtain a time and spatial part. The spatial part is in effect the time independent schrodinger equation.



Since we are dealing with a free particle I can take the time independent equation, set V = 0 and solve.



I can do this successfully to obtain :



[itex]Ae^{+i\sqrt{{2mE}/{\hbar^{2}}}x}+Be^{-i\sqrt{{2mE}/{\hbar^{2}}}x}[/itex]



My lecturer has a small section titled :




Quote:








>Solving for the Free Schrodinger Equation



[itex]V=0[/itex]



[itex]\frac{\hbar^{2}}{2m}\frac{\partial^2\psi}{\partial x^2}+E\psi=0[/itex]



[itex]E=\frac{p^2}{2m}[/itex]



[itex]\psi=Ce^{-{iEt}/{\hbar}+{ipr}/{\hbar}}[/itex]



This is the solution to the free TISE and TDSE.



So when I follow through and solve for the spatial part of his final solution I obtain :



[itex]A'e^{+ip/\hbar}+B'e^{-ip/\hbar}[/itex]



He seems to have conveniently ignored/left out one half of the above solution. Why ?



I am also aware that [itex]e^{-{iEt}/{\hbar}}[/itex] is simply the solution the time dependent part of the equation so my only issue is why he has left out a certain bit.





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