Formulas

$\hbar = 1.05 \times 10^{-27} \mathrm{erg\; sec}$	$c = 3.00 \times 10^{10} \mathrm{cm/sec}$	$e = 1.602 \times 10^{-19} \mathrm{Coulomb}$
$1 eV = 1.602 \times 10^{-12} \mathrm{erg}$	$\alpha = {e^2\over \hbar c} = {1\over 137} = {e^2\over 4\pi\epsilon_0\hbar c} \mathrm{(SI)}$	$\hbar c = 1973 \mathrm{eV\; \AA} = 197.3 \mathrm{MeV\; F}$
$1 \mathrm{\AA} = 1.0 \times 10^{-8} \mathrm{cm}$	$1 \mathrm{Fermi} = 1.0 \times 10^{-13} \mathrm{cm}$	$a_0 = {\hbar\over \alpha m_e c} = 0.529 \times 10^{-8} \mathrm{cm}$
$m_p = 938.3 \mathrm{MeV}/c^2$	$m_n = 939.6 \mathrm{MeV}/c^2$	$m_e = 9.11 \times 10^{-28} \mathrm{g} = 0.511 \mathrm{MeV}/c^2$
$k_B = 1.38 \times 10^{-16} \mathrm{erg}/^{\circ} \mathrm{K}$	$g_e = 2 + {\alpha\over\pi}$	$g_p = 5.6$
$\mu_{Bohr} = {e\hbar\over 2m_e c} = 0.579 \times 10^{-8} \mathrm{eV/gauss}$		$\int\limits_{-\infty}^\infty dx\; f(x)\; \delta(g(x))=\left[{1\over \vert{dg\over dx}\vert}f(x)\right]_{g(x)=0}$
$\int\limits_{-\infty}^\infty dx\; f(x)\; \delta(x-a)=f(a)$	$\int\limits_{-\infty}^{\infty}\; dx\; e^{-ax^2} = \sqrt{\pi\over a}$	use ${\partial\over\partial a}$ for other forms
$e^A=\sum\limits_{n=0}^\infty {A^n\over n!}$	$\sin\theta= \sum\limits_{n=1,3,5...}^\infty {\theta^n\over n!}(-1)^{{n-1\over 2}}$	$\cos\theta= \sum\limits_{n=0,2,4...}^\infty {\theta^n\over n!}(-1)^{{n\over 2}}$
$P(x)={1\over\sqrt{2\pi\sigma^2}}e^{-x^2/2\sigma^2}$	$\int\limits_0^\infty dr\; r^n e^{-ar}={n!\over a^{n+1}}$	$E=\sqrt{m^2c^4+p^2c^2}$

GENERAL WAVE MECHANICS
$E=h\nu=\hbar\omega$                 Ref.	$\lambda = h/p$                 Ref.	$p=\hbar k$
$\Delta p\; \Delta x \geq {\hbar\over 2}$                 Ref.	$\Delta A\; \Delta B \geq \langle{i\over 2} [A,B]\rangle$                 Ref.	$\Delta A=\sqrt{\langle A^2\rangle-\langle A\rangle^2}$
$\psi (x) = {1\over\sqrt{2\pi \hbar}} \int\limits_{-\infty}^{\infty}dp\; \phi (p)\; e^{ipx/\hbar}$                 Ref.		$\phi (p) = {1\over\sqrt{2\pi \hbar}} \int\limits_{-\infty}^{\infty}dx\; \psi (x)\; e^{-ipx/\hbar}$
$p_{op} = {\hbar\over i}{\partial\over \partial x}$                 Ref.	$E_{op} = i\hbar {\partial\over \partial t}$                 Ref.	$x_{op} = i\hbar {\partial\over \partial p}$                 Ref.
$Hu_j(x)=E_ju_j(x)$	$\psi_j(x,t)=u_j(x)e^{-iE_jt/\hbar}$                 Ref.	${-\hbar^2\over 2m}{\partial^2\psi\over\partial x^2}+V(x)\psi=i\hbar{\partial\psi\over\partial t}$
$\psi(x)$ continuous	${d\psi\over dx}$ continous if $V$ finite                 Ref.
$\Delta{d\psi\over dx}={2m\lambda\over\hbar^2}\psi(a)$ for $V(x)=\lambda\delta(x-a)$                 Ref.
$\langle\phi\vert\psi\rangle=\int\limits_{-\infty}^\infty dx \phi^*(x)\psi(x)$	$\langle u_i\vert u_j\rangle=\delta_{ij}$                 Ref.	$\sum\limits_i\vert u_i\rangle\langle u_i\vert=1$                 Ref.
$\phi=\sum\limits_ia_iu_i$	$a_i=\langle u_i\vert\phi\rangle$	$\psi(x)=\langle x\vert\psi\rangle$                 Ref.
$\langle\phi\vert A\vert\psi\rangle= \langle\phi\vert A\psi... ...\dagger\phi\vert\psi\rangle=\langle\psi\vert A^\dagger\vert\phi\rangle^*$                 Ref.		$\phi(p)=\langle p\vert\psi\rangle$                 Ref.
$\lbrack{1\over 2m}(\vec{p}+{e\over c}\vec{A})^2 + V(\vec{r})\rbrack \psi(\vec{r}) = E \psi(\vec{r})$		$H\psi=E\psi$                 Ref.
$[p_x,x]={\hbar\over i}$	$[L_x,L_y] = i \hbar L_z$	$[L^2,L_z] = 0$
$\psi_i=\langle u_i\vert\psi\rangle$                 Ref.	$A_{ij}=\langle u_i\vert A\vert u_j\rangle$                 Ref.	${d\langle A\rangle \over dt}= \langle {\partial A\over \partial t}\rangle +{i\over \hbar}\langle [H,A]\rangle$                 Ref.

HARMONIC OSCILLATOR
$H = {p^2\over 2m}+{1\over2}m\omega^2x^2 = \hbar\omega A^\dagger A + {1\over 2}\hbar\omega$                 Ref.		$E_n = (n + {1\over 2}) \hbar \omega \quad n=0,1,2...$ Ref.
$u_n(x)=\sum\limits_{k=0}^\infty a_ky^ke^{-y^2/2}$	$a_{k+2}={2(k-n)\over (k+1)(k+2)}a_k$	$y=\sqrt{m\omega\over\hbar}x$
$A = (\sqrt{m\omega\over 2\hbar} x + i {p\over\sqrt{2 m \hbar\omega}})$	$A^\dagger = (\sqrt{m\omega\over 2\hbar} x - i {p\over\sqrt{2 m \hbar\omega}})$	$[A,A^\dagger] = 1$
$A^\dagger\; \vert n\rangle = \sqrt{(n+1)}\; \vert n+1\rangle$	$A\; \vert n\rangle = \sqrt{(n)}\; \vert n-1\rangle$	$u_0 (x) = ({m\omega\over \hbar \pi})^{1\over 4}\; e^{-m\omega x^2/2\hbar}$

ANGULAR MOMENTUM
$[L_i,L_j]=i\hbar\epsilon_{ijk}L_k$                 Ref.	$[L^2,L_i]=0$	$\int Y_{\ell m}^* Y_{\ell' m'} d\Omega=\delta_{\ell\ell'}\delta_{mm'}$
$L^2 Y_{\ell m} = \ell (\ell +1)\hbar^2 Y_{\ell m}$	$L_z Y_{\ell m} = m\hbar Y_{\ell m}$	$-\ell\leq m\leq\ell$                 Ref.
$L_\pm=L_x\pm iL_y$	$L_\pm Y_{\ell m} = \hbar \sqrt{\ell (\ell +1) - m(m\pm 1)}\; Y_{\ell ,m\pm 1}$
$Y_{00}={1\over\sqrt{4\pi}}$                 Ref.	$Y_{11} = -\sqrt{3\over 8\pi}\; e^{i\phi}\; \sin\theta$	$Y_{10} = \sqrt{3\over 4\pi}\; \cos\theta$
$Y_{22} = \sqrt{15\over 32\pi}\; e^{2i\phi}\; \sin^2\theta$	$Y_{21} = -\sqrt{15\over 8\pi}\; e^{i\phi}\; \sin\theta \cos\theta$	$Y_{20} = \sqrt{5\over 16\pi}\; (3 \cos^2\theta-1)$
$Y_{\ell\ell} = e^{i\ell\phi}\; \sin^\ell \theta$	$Y_{\ell(-m)}=(-1)^m Y_{\ell m}^*$	$Y_{\ell m}(\pi -\theta ,\phi +\pi) = (-1)^\ell \; Y_{\ell m}(\theta ,\phi )$
${-\hbar^2\over 2\mu}\left[{\partial^2\over\partial r^2}+{2\... ...r)+{\ell(\ell+1)\hbar^2\over 2\mu r^2}\right)R_{n\ell}(r)=ER_{n\ell}(r)$                 Ref.
$j_0(kr)={\sin(kr)\over kr}$                 Ref.	$n_0(kr)=-{\cos(kr)\over kr}$	$h_\ell^{(1)}(kr)=j_\ell(kr)+in_\ell(kr)$
$H = H_0 - \vec{\mu} \cdot \vec{B}$                 Ref.	$\vec{\mu} = {e\over 2mc}\vec{L}$	$\vec{\mu} = {ge\over 2mc}\vec{S}$
$S_i = {\hbar\over 2} \sigma_i$	$[\sigma_i,\sigma_j]=2i\epsilon_{ijk}\sigma_k$	$\{\sigma_i,\sigma_j\}=0$
$\sigma_x = \pmatrix{0 &1\cr 1 &0\cr}$	$\sigma_y = \pmatrix{0 &-i\cr i &0\cr}$	$\sigma_z = \pmatrix{1 &0\cr 0 &-1\cr}$                 Ref.
$S_x=\hbar\pmatrix{0&{1\over \sqrt{2}}&0 \cr {1\over \sqrt{2}}&0&{1\over \sqrt{2}} \cr 0&{1\over \sqrt{2}}&0}$	$S_y=\hbar\pmatrix{0&{-i\over \sqrt{2}}&0 \cr {i\over \sqrt{2}}&0&{-i\over \sqrt{2}} \cr 0&{i\over \sqrt{2}}&0}$	$S_z=\hbar\pmatrix{1&0&0\cr 0&0&0\cr 0&0&-1}$                 Ref.

HYDROGEN ATOM
$H = {p^2\over 2\mu}-{Ze^2\over r}$	$\psi_{n\ell m} = R_{n\ell}(r) Y_{\ell m}(\theta,\phi)$	$E_n = -{Z^2 \alpha^2 \mu c^2\over 2 n^2}=-{13.6\over n^2}$ eV
$n=n_r+\ell+1$                 Ref.	$a_0={\hbar\over\alpha\mu c}$	$\ell=0,1,...,n-1$
$R_{n\ell}(\rho)=\rho^\ell\sum\limits_{k=0}^\infty a_k\rho^k e^{-\rho/2}$	$a_{k+1}={k+\ell+1-n\over (k+1)(k+2\ell+2)}a_k$         Ref.	$\rho=\sqrt{-8\mu E\over\hbar^2}r={2r\over na_0}$
$R_{10} = 2({Z\over a_0})^{3\over 2}\; e^{-Zr\over a_0}$                 Ref.	$R_{20} = 2({Z\over 2a_0})^{3\over 2} (1-{Zr\over 2a_0})\;e^{-Zr\over 2a_0}$	$R_{21} = {1\over\sqrt 3}({Z\over 2a_0})^{3\over 2} ({Zr\over a_0})\;e^{-Zr\over 2a_0}$
$R_{n,n-1}\; \propto\; r^{n-1}\; e^{-Zr/na_0}$	$\mu = {m_1 m_2\over m_1 + m_2}$                 Ref.	$\langle\psi_{n\ell m}\vert{e^2\over r}\vert\psi_{n\ell m}\rangle={Ze^2\over n^2a_0}={Z\alpha^2\mu c^2\over n^2}$
$H_1=-{p^4\over 8m^3c^2}$                 Ref.	$H_2={e^2\over 2m^2c^2r^3}\vec{S}\cdot\vec{L}$                 Ref.	$\Delta E_{12}=-{1\over 2n^3}\alpha^4mc^2\left({1\over j+{1\over 2}}-{3\over 4n}\right)$         Ref.
$H_3={-e^2g_p\over 3mM_pc^2}\vec{S}\cdot\vec{I}\delta({r})$	$\Delta E_{3}={2g_pm\alpha^4mc^2\over 3M_pn^3}(f(f+1)-I(I+1)-{3\over 4})$                 Ref.
$H_B={eB\over 2mc}(L_z+2S_z)$                 Ref.	$\Delta E_B={e\hbar B\over 2mc}(1\pm {1\over 2\ell +1})m_j$ for $j=\ell\pm{1\over 2}$

ADDITION OF ANGULAR MOMENTUM
$\vec{J} = \vec{L}+\vec{S}$	$\vert\ell -s\vert \leq j \leq \ell +s$                 Ref.	$\vec{L\cdot S}={1\over 2}(J^2-L^2-S^2)$
$\psi_{jm_j\ell s}= \sum\limits_{m_\ell m_s}\langle j m_j \ell s\vert\ell m_\ell s m_s\rangle Y_{\ell m_\ell}\chi_{sm_s}$                 Ref.
$\psi_{j,m_j}=\psi_{\ell +{1\over 2},m+{1\over 2}}= \sqrt{\... ...ell +1}Y_{\ell m}\chi_+ +\sqrt{\ell -m\over 2\ell +1}Y_{\ell ,m+1}\chi_-$                 Ref.		for $s={1\over 2}$ and any $\ell$
$\psi_{j,m_j}=\psi_{\ell -{1\over 2},m+{1\over 2}}= \sqrt{\... ... +1}Y_{\ell m}\chi_+ -\sqrt{\ell +m+1\over 2\ell +1 }Y_{\ell ,m+1}\chi_-$		for $s={1\over 2}$ and any $\ell$

PERTURBATION THEORY AND RADIATIVE DECAYS
$E_n^{(1)}=\langle \phi_n\vert H_1\vert\phi_n\rangle$                 Ref.	$E_n^{(2)}=\sum\limits_{k\neq n}{\vert\langle \phi_k\vert H_1\vert\phi_n\rangle \vert^2\over E_n^{(0)}-E_k^{(0)}}$	$c_{nk}^{(1)}={\langle \phi_k\vert H_1\vert\phi_n\rangle \over E_n^{(0)}-E_k^{(0)}}$
$c_n(t) = {1\over i\hbar} \int\limits_{0}^{t}\; dt'\; e^{i(E_n-E_i)t'/\hbar}\langle \phi_n\vert V(t')\vert\phi_i\rangle$                 Ref.
Fermi's Golden Rule:	$\Gamma_{i\rightarrow f}={2\pi\over\hbar}\vert\langle \psi_f\vert V\vert\psi_i\rangle \vert^2\rho_f(E)$                 Ref.
$\Gamma_{i\rightarrow f} = {2\pi\over \hbar} \int\; \prod\l... ...({Vd^3{p_k}\over \rm (2\pi \hbar)^3}) \;\vert M_{fi}\vert^2\; \delta^3($momentum conservation $) \; \delta$(Energy conservation)
$\Gamma^{rad}_{m\rightarrow k} = {\alpha\over 2\pi m^2c^2}\... ...t\vec{r}}\vec{\epsilon}^{(\lambda)}\cdot\vec{p}\vert\phi_k\rangle\vert^2$                 Ref.
$\Gamma^{E1}_{m\rightarrow k} = {\alpha\over 2\pi c^2}\sum\... ...i_m\vert\vec{\epsilon}^{(\lambda)}\cdot\vec{r}\vert\phi_k\rangle \vert^2$                 Ref.		$\Delta l=\pm 1$, $\Delta s=0$
$\hat{\epsilon}\cdot \hat{r}=\sqrt{4\pi\over 3}(\epsilon_zY_... ...ilon_y\over\sqrt{2}}Y_{11}+{\epsilon_x+i\epsilon_y\over\sqrt{2}}Y_{1-1})$		$\vec{\epsilon}\cdot\vec{k}=0$
$I(\omega)\propto{\Gamma/2\over (\omega-\omega_0)^2+(\Gamma/2)^2}$                 Ref.	$\Gamma_{collision}=P\sigma\sqrt{3\over mkT}$	$({\Delta\omega\over\omega})_{Dopler}=\sqrt{kT\over mc^2}$
$\Gamma_{tot}={4\alpha\omega_{in}^3\over 3c^2}\left\{\matrix... ...\qquad \mathrm{ for}\qquad \ell'=\left\{\matrix{\ell+1\cr \ell-1}\right.$                 Ref.
$({d\sigma\over d\Omega})_{BORN}={1\over 4\pi^2 \hbar^4}{p_f\over p_i}m_f m_i \vert{\tilde V}(\vec{\Delta}$ $)\vert^2$	${\tilde V}(\vec{\Delta}$ $) = \int \; d^3 \vec{r}\;e^{-i \vec{\Delta}\cdot\vec{r}}\;V(\vec{r}$ $)$	$\vec{\Delta}={\vec{p_f}-\vec{p_i}\over\hbar}$                 Ref.

ELECTRICITY AND MAGNETISM
$\vec{\nabla}\cdot\vec{B} = 0$	$\vec{\nabla}\times\vec{E}+{1\over c}{\partial \vec{B}\over\partial t}=0$	$\vec{\nabla}\cdot\vec{E}=4\pi\rho$
$\vec{\nabla}\times\vec{B}-{1\over c}{\partial \vec{E}\over\partial t}={4\pi\over c}\vec{J}$	$\vec{F}=-e(\vec{E}+{1\over c}\vec{v}\times\vec{B})$	$H={p^2\over 2m}\rightarrow{1\over 2m}\left(\vec{p}+{e\over c}\vec{A}\right)^2-e\phi$
$\vec{B}=\vec{\nabla}\times \vec{A}$	$\vec{E}=-\vec{\nabla}\phi-{1\over c}{\partial \vec{A}\over\partial t}$	$-\nabla^2\phi-{1\over c}{\partial\over\partial t}(\vec{\nabla}\cdot\vec{A})=4\pi\rho$
$\psi(\vec{r},t) \to e^{i\lambda(\vec{r},t)}\psi(\vec{r},t)$	$\vec{A} \to \vec{A}-\vec{\nabla}f(\vec{r},t)$	$-\nabla^2\vec{A}+{1\over c^2}{\partial^2\vec{A}\over\partia... ...A}+{1\over c}{\partial\phi\over\partial t}\right) ={4\pi\over c}\vec{J}$
$\phi \to \phi+{1\over c}{\partial f(\vec{r},t)\over\partial t}$	$f(\vec{r},t) = {\hbar c\over e}\lambda(\vec{r},t)$
${-\hbar^2\over 2m}\nabla^2\psi+{e\over 2mc}\vec{B}\cdot\vec... ...er 8mc^2} \left(r^2B^2-(\vec{r}\cdot\vec{B})^2\right)\psi=(E+e\phi)\psi$

ATOMS AND MOLECULES
Hund: 1) max $s$	2)max $\ell$ (allowed)	3) min $j$ $(\leq {1\over 2}$ shell) else max $j$
$E_{rot}={\ell (\ell +1)\hbar^2\over 2I}\approx {1\over 2000}$ eV	$E_{vib}=(n+{1\over 2})\hbar\omega\approx {1\over 50}$ eV