numexercises7_15
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numexercises7_15 [2014/07/15 08:47] bogner |
numexercises7_15 [2014/07/18 05:04] (current) schunck |
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| Recall that the HO wavefunctions are given by | Recall that the HO wavefunctions are given by | ||
| \begin{equation} | \begin{equation} | ||
| - | R_{nl}(r) = \frac{A_{nl}}{b^{3/2}}x^le^{-x^2/2}L_{n}^{l+1/2}(x^2)\,, | + | R_{nl}(r) = \frac{A_{nl}}{b^{3/2}}\xi^le^{-\xi^2/2}L_{n}^{l+1/2}(\xi^2)\,, |
| \end{equation} | \end{equation} | ||
| - | where the oscillator length $b\equiv \sqrt{\hbar/(m\omega)}$, and the dimensionless variable $x\equiv r/b$. The normalization constant is given by | + | where the oscillator length $b\equiv \sqrt{\hbar/(m\omega)}$, and the dimensionless variable $\xi\equiv r/b$. The normalization constant is given by |
| \begin{equation} | \begin{equation} | ||
| Line 48: | Line 48: | ||
| * Now, write a subroutine to evaluate the matrix elements $\langle nl|V|n'l\rangle$ for some arbitrary central two-body potential $V(r)$. | * Now, write a subroutine to evaluate the matrix elements $\langle nl|V|n'l\rangle$ for some arbitrary central two-body potential $V(r)$. | ||
| - | * To test your \langle nl|V|n'l\rangle$ routine, apply it to the coulomb potential in the hydrogen atom problem. Use atomic units ($\hbar=e=1/4\pi\epsilon_0=m_e$). Now, build the Hamiltonian matrix $\langle nl|H|n'l\rangle$ (you may take $l=0$) for the hydrogen atom, keeping states $n,n'< N_{max}$. Use the analytic expressions for the K.E. matrix elements in {{:ho_spherical.pdf|}}. Now diagonalize the matrix to get the ground state energy. | + | * To test your $\langle nl|V|n'l\rangle$ routine, apply it to the coulomb potential in the hydrogen atom problem. Use atomic units ($\hbar=e=1/4\pi\epsilon_0=m_e=1$). Now, build the Hamiltonian matrix $\langle nl|H|n'l\rangle$ (you may take $l=0$) for the hydrogen atom, keeping states $n,n'< N_{max}$. Use the analytic expressions for the K.E. matrix elements in {{:ho_spherical.pdf|}}. Now diagonalize the matrix to get the ground state energy. |
| * For a given $N_{max}$, repeat the calculation for many different values of oscillator length and plot the ground state versus $b$. Repeat for larger values of $N_{max}$ and put the $E$ versus $b$ curves on the same plot. Are they behaving according to expectation? (Hint: the diagonalization in a finite basis is variational.) Should results depend on $b$ as $N_{max}\rightarrow\infty$? | * For a given $N_{max}$, repeat the calculation for many different values of oscillator length and plot the ground state versus $b$. Repeat for larger values of $N_{max}$ and put the $E$ versus $b$ curves on the same plot. Are they behaving according to expectation? (Hint: the diagonalization in a finite basis is variational.) Should results depend on $b$ as $N_{max}\rightarrow\infty$? | ||
numexercises7_15.1405428460.txt.gz · Last modified: 2014/07/15 08:47 by bogner
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