#This file was created by Sun Feb 11 22:59:24 2001 #LyX 0.12 (C) 1995-1998 Matthias Ettrich and the LyX Team \lyxformat 2.15 \textclass amsart \begin_preamble \pretolerance=2000 \tolerance=3000 \usepackage{ae} \end_preamble \language spanish \inputencoding latin1 \fontscheme default \graphics default \paperfontsize 9 \spacing single \papersize a4paper \paperpackage a4 \use_geometry 1 \use_amsmath 0 \paperorientation portrait \leftmargin 15pt \topmargin 10pt \rightmargin 10pt \bottommargin 15pt \secnumdepth 3 \tocdepth 3 \paragraph_separation skip \defskip smallskip \quotes_language english \quotes_times 2 \papercolumns 2 \papersides 1 \paperpagestyle default \layout Section* tema 1. Estructura Cristalina. \layout Standard \align left Posicion de un punto de la red: \begin_inset Formula \( \vec{r}=n_{1}\vec{a}_{1}+n_{2}\vec{a}_{2}+n_{3}\vec{a}_{3} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Volumen de la celda unidad: \begin_inset Formula \( V=\left| \vec{a}\cdot \vec{b}\times \vec{c}\right| \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Distancia entre planos (SC, BCC, FCC): \begin_inset Formula \( d_{hkl}=\frac{a}{\sqrt{h^{2}+k^{2}+l^{2}}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Red Ortorrómbica: \begin_inset Formula \( d_{hkl}=\frac{1}{\sqrt{\frac{h^{2}}{a^{2}}+\frac{k^{2}}{b^{2}}+\frac{l^{2}}{c^{2}}}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Estructuras cristalinas simples. \series default i) NaCl (FCC). Cl: \begin_inset Formula \( 000,\frac{1}{2}\frac{1}{2}0,\frac{1}{2}0\frac{1}{2},0\frac{1}{2}\frac{1}{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Na: \begin_inset Formula \( \frac{1}{2}\frac{1}{2}\frac{1}{2},00\frac{1}{2},0\frac{1}{2}0,\frac{1}{2}00 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset ii) CsCl (SC) Cs: \begin_inset Formula \( 000 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Cl: \begin_inset Formula \( \frac{1}{2}\frac{1}{2}\frac{1}{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset iii) hcp: Factor de empaquetamiento: \begin_inset Formula \( c/a=(8/3)^{1/2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset iv) Estructura diamante (FCC). \begin_inset Formula \( 000,\frac{1}{2}\frac{1}{2}\frac{1}{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset v) ZnS (2FCC). Zn: \begin_inset Formula \( 000,0\frac{1}{2}\frac{1}{2},\frac{1}{2}0\frac{1}{2},\frac{1}{2}\frac{1}{2}0 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset S: \begin_inset Formula \( \frac{1}{4}\frac{1}{4}\frac{1}{4},\frac{1}{4}\frac{3}{4}\frac{3}{4},\frac{3}{4}\frac{1}{4}\frac{3}{4},\frac{3}{4}\frac{3}{4}\frac{1}{4} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Volúmenes celdas primitivas: i) SC: \begin_inset Formula \( V=a^{3} \) \end_inset ii) BCC: \begin_inset Formula \( V=a^{3}/2 \) \end_inset iii) FCC: \begin_inset Formula \( V=a^{3}/4 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Coefiiente de dilatación lineal: \begin_inset Formula \( L'=L_{0}(1+\alpha \Delta T) \) \end_inset \layout Section* tema 2. Difracción. \layout Standard \align left Ley de Bragg: \begin_inset Formula \( 2d\sin \theta =n\lambda \) \end_inset , intensidad máxima \begin_inset Formula \( n=1 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Red Real \begin_inset Formula \( \rightarrow \) \end_inset \begin_inset Formula \( a \) \end_inset , Red Recíproca \begin_inset Formula \( \rightarrow \) \end_inset \begin_inset Formula \( 2\pi /a \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Número de electrones en la red \layout Standard \align left periódica: \begin_inset Formula \( n(\vec{r})=\sum _{G}n_{G}\exp (-i\vec{G}\cdot \vec{r}) \) \end_inset con \begin_inset Formula \( n_{G}=\frac{1}{V_{c}}\int _{c}dVn(\vec{r})\exp (-i\vec{G}\cdot \vec{r}) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Vector de la red recíproca: \begin_inset Formula \( G=h\vec{b}_{1}+k\vec{b}_{2}+l\vec{b}_{3} \) \end_inset con \begin_inset Formula \( \vec{b}_{1}=2\pi \frac{\vec{a}_{2}\times \vec{a}_{3}}{\vec{a}_{1}\cdot \vec{a}_{2}\times \vec{a}_{3}} \) \end_inset , \begin_inset Formula \( \vec{b}_{2}=2\pi \frac{\vec{a}_{3}\times \vec{a}_{1}}{\vec{a}_{1}\cdot \vec{a}_{2}\times \vec{a}_{3}} \) \end_inset , \begin_inset Formula \( \vec{b}_{3}=2\pi \frac{\vec{a}_{1}\times \vec{a}_{2}}{\vec{a}_{1}\cdot \vec{a}_{2}\times \vec{a}_{3}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \vec{b}_{i}\cdot \vec{a}_{j}=2\pi \delta _{ij} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Amplitud de \emph on Scattering \emph toggle : \begin_inset Formula \( F=\sum _{G}\int dVn_{g}e^{i(\vec{G}-\Delta \vec{k})\vec{r}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Condición de difracción: \begin_inset Formula \( \Delta \vec{k}=\vec{G} \) \end_inset , si elástica \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( 2\vec{k}\vec{G}=G^{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( d_{hkl}=2\pi /\left| \vec{G}\right| \) \end_inset . Si \begin_inset Formula \( \Delta \vec{k}=\vec{G} \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( F_{G}=N\int _{c}dVn(\vec{r})e^{-i\vec{G}\cdot \vec{r}}=NS_{G} \) \end_inset , con \begin_inset Formula \( S_{G}\equiv \) \end_inset Factor de Esctructura \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( n(\vec{r})=\sum ^{s}_{j=1}n_{j}(\vec{r}-\vec{r}_{j})=\sum ^{s}_{j=1}n_{j}(\vec{\rho }) \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( S_{G}=\sum _{j}\int dVn_{j}(\vec{r}-\vec{r}_{j})\exp (-i\vec{G}\cdot \vec{r}) \) \end_inset \begin_inset Formula \( =\sum _{j}\exp (-i\vec{G}\cdot \vec{r}_{j})\int dvn_{j}(\vec{\rho })\exp (-i\vec{G}\cdot \vec{\rho }) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Factor atómico de forma: \begin_inset Formula \( f_{j}=\int dVn_{j}(\vec{\rho })\exp (-i\vec{G}\cdot \vec{\rho }) \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( S_{G}=\sum _{j}f_{j}\exp (-i\vec{G}\cdot \vec{r}) \) \end_inset y también \begin_inset Formula \( S_{G}=\sum _{j}f_{j}\exp \{-i(hn_{1}+kn_{2}+ln_{3}) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Anillos de difracción: \begin_inset Formula \( d_{hkl}=\lambda /2 \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( \sin \theta _{max}=\pi /2 \) \end_inset , aparecen anillos para \begin_inset Formula \( d_{hkl}\geq \lambda /2 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Factor atómico de forma, distribución esférica de carga: \begin_inset Formula \( f_{j}=4\pi \int _{0}^{\infty }drr^{2}n_{j}(r)\frac{\sin Gr}{Gr} \) \end_inset \begin_inset Formula \( \bullet \int _{0}^{\infty }dxx^{n}e^{-ax}=\frac{\Gamma (n+1)}{a^{n+1}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \Gamma (n+1)=n\Gamma (n)=n! \) \end_inset \begin_inset Formula \( \bullet \) \end_inset BCC: \begin_inset Formula \( S_{G,BCC}=f_{BCC}\left( 1+(-1)^{h+k+l}\right) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset FCC: \begin_inset Formula \( S_{G,FCC}=f_{FCC}\left( 1+(-1)^{h+k}+(-1)^{k+l}+(-1)^{h+l}\right) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Intensidad de difracción: \begin_inset Formula \( I=S_{G}\cdot S_{G}^{*} \) \end_inset \layout Section* tema 3. Enlace Cristalino. \layout Standard \align left \series bold \begin_inset Formula \( U_{T}=U_{atrac}+U_{repuls} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Potenciales repulsivos: \series default i) Potencial de Lenard-Jones: \begin_inset Formula \( U_{R}=B/R^{12} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset ii) Potencial de Born-Mayer: \begin_inset Formula \( U^{'}_{R}=\lambda \exp (-R/\rho ) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Cristales inertes ( \emph on Van der Waals \emph toggle ): \series default Potencial de interacción de una pareja de átomos: \begin_inset Formula \( U_{ij}=B/R_{ij}^{12}-A/R_{ij}^{6}=4\epsilon \left[ \left( \sigma /R_{ij}\right) ^{12}-\left( \sigma /R_{ij}\right) ^{6}\right] \) \end_inset , con \begin_inset Formula \( \sigma =(B/A)^{1/6}\equiv \) \end_inset parámetro de distancia; \begin_inset Formula \( \epsilon =A^{2}/4B\equiv \) \end_inset parámetro de energía \begin_inset Formula \( \bullet \) \end_inset Energía total: \begin_inset Formula \( U_{T}=2N\epsilon \left[ \sum _{j\neq i}\left( \sigma /R_{ij}\right) ^{12}-\sum _{j\neq i}\left( \sigma /R_{ij}\right) ^{6}\right] \) \end_inset \begin_inset Formula \( \rightarrow \) \end_inset \begin_inset Formula \( R_{ij}=\rho _{ij}R \) \end_inset . \begin_inset Formula \( R\equiv \) \end_inset distancia entre vecinos más próximos \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( U_{T}(R)=2N\epsilon \left[ A_{12}(\sigma /R)^{12}-A_{6}(\sigma /R)^{6}\right] \equiv \) \end_inset Energía total de interacción o Energía de Cohesión. \begin_inset Formula \( \bullet \) \end_inset FCC: \begin_inset Formula \( A_{12}=12.13188 \) \end_inset , \begin_inset Formula \( A_{6}=14.45392 \) \end_inset . HCP: \begin_inset Formula \( A_{12}=12.13229 \) \end_inset , \begin_inset Formula \( A_{6}=14.4589 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Parámetro de red: \begin_inset Formula \( \left. \frac{dU_{T}(R)}{dR}\right\rfloor _{R=R_{0}}=0\Rightarrow R_{0}=2\left( \frac{A_{12}}{A_{6}}\right) ^{1/6}\sigma \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Cristales iónicos: \series default Interacción electrostática: \begin_inset Formula \( U_{elec}=\sum _{j\neq i}\frac{\pm Q^{2}}{4\pi \epsilon _{0}R_{ij}} \) \end_inset (SI), \begin_inset Formula \( U_{elec}=\sum _{j\neq i}\frac{\pm Q^{2}}{R_{ij}} \) \end_inset (CGS) \begin_inset Formula \( \bullet \) \end_inset Energía total: \begin_inset Formula \( U_{Total}(R)=N\left[ -\frac{Q^{2}}{4\pi \epsilon _{0}R}\sum _{j\neq i}\frac{\pm 1}{P_{ij}}+z\lambda e^{-R/\rho }\right] \) \end_inset con \begin_inset Formula \( \alpha =\sum _{i\neq j}\frac{\pm 1}{P_{ij}}\equiv \) \end_inset Constante de Madelung, tb \begin_inset Formula \( \frac{\alpha }{R}=\sum _{j}\frac{1}{r_{ij}} \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( U_{TOT}(R)=-\frac{NQ^{2}\alpha }{4\pi \epsilon _{0}R}+zN\lambda e^{-R/\rho } \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Energía de Cohesión: \begin_inset Formula \( U(R_{0})=-\frac{NQ^{2}\alpha }{4\pi \epsilon _{0}R_{0}}\left[ 1-\rho /R_{0}\right] \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( Na+PI\rightarrow Na^{+}+e^{-} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( e^{-}+Cl\rightarrow Cl^{-}+AE \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( Na+Cl\rightarrow NaCl+E_{cohesi\acute{o}n} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Cristal iónico lineal: \begin_inset Formula \( U_{Tot}=N\left[ \frac{A}{R^{N}}-\frac{\alpha q^{2}}{R}\right] \) \end_inset \series bold \begin_inset Formula \( \bullet \) \end_inset Cristales covalentes: \series default Singlete-Enlazante. Triplete-Antienlazante. \begin_inset Formula \( \bullet \) \end_inset \series bold Cristales Metálicos. \layout Section* Tema 4. Fonones. Vibraciones de la red. \layout Standard \align left Ecuación de movimiento: \begin_inset Formula \( m\frac{d^{2}u_{n}}{dt^{2}}=\sum _{p}C_{p}(u_{n+p}-u_{n}) \) \end_inset , soluciones: Modos normales: \series bold \series default \begin_inset Formula \( u_{n}(x,t)=u_{0}e^{i(kx-\omega t)} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Relación de dispersión: \begin_inset Formula \( \omega ^{2}=\sum _{p}2C_{p}\frac{1}{m}\left[ 1-\cos kpa\right] \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Interacción a primeros vecinos, \begin_inset Formula \( p=1 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( x=sa \) \end_inset con \begin_inset Formula \( s=0,1,... \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( u_{n+1}=u_{n}(x+a) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( m\frac{d^{2}u_{s}}{dt^{2}}=C(u_{s+1}+u_{s-1}-2u_{s}) \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( \omega =\sqrt{\frac{4C_{1}}{m}}\left| \sin \frac{ka}{2}\right| \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \omega _{max}=\omega (k=\pm \pi /a)=\sqrt{4C_{1}/m} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset 1ª Zona de Brillouin: \begin_inset Formula \( -\pi \leq ka\leq \pi \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Condición de Bragg: \begin_inset Formula \( k_{max}=\pm k/a \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Velocidad de grupo: \begin_inset Formula \( v_{g}=\frac{d\omega }{dk} \) \end_inset (1D), \begin_inset Formula \( v_{g}=\nabla _{\vec{k}}\omega (\vec{k}) \) \end_inset (3D). \begin_inset Formula \( v_{g}=\sqrt{\frac{C_{1}a^{2}}{m}}\left| \cos \frac{ka}{2}\right| \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Aproximación de onda larga: \begin_inset Formula \( ka\ll 1\Rightarrow \sin \frac{ka}{2}\simeq \frac{ka}{2} \) \end_inset . Así pues, \begin_inset Formula \( \omega ^{2}=\frac{C_{1}}{m}k^{2}a^{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Dos átomos por celda primitiva: \series default Ecuaciones de movimiento: \begin_inset Formula \( m_{1}\frac{d^{2}u_{s}}{dt^{2}}=C(v_{s}+v_{s-1}-2u_{s}) \) \end_inset , \begin_inset Formula \( m_{2}\frac{d^{2}v_{s}}{dt^{2}}=C(u_{s+1}+u_{s}-2v_{s}) \) \end_inset . Soluciones (modos normales): \begin_inset Formula \( u_{s}=u_{0}e^{iska}e^{-i\omega t} \) \end_inset , \begin_inset Formula \( v_{s}=v_{0}e^{iska}e^{-i\omega t} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Relación de dispersión: \begin_inset Formula \( \omega _{\pm }^{2}=C\left( \frac{m_{1}+m_{2}}{m_{1}m_{2}}\right) \pm C\sqrt{\left( \frac{m_{1}+m_{2}}{m_{1}m_{2}}\right) ^{2}-\frac{4}{m_{1}m_{2}}\sin ^{2}\frac{ka}{2}} \) \end_inset . \begin_inset Formula \( \omega _{+}\rightarrow \) \end_inset Rama óptica, \begin_inset Formula \( \omega _{-}\rightarrow \) \end_inset Rama acústica. \begin_inset Formula \( \bullet \) \end_inset Aproximación de onda larga \begin_inset Formula \( (ka\ll 1) \) \end_inset : \begin_inset Formula \( \omega _{+}^{2}\simeq 2C\frac{m_{1}+m_{2}}{m_{1}m_{2}} \) \end_inset . \begin_inset Formula \( \omega _{-}^{2}\simeq \frac{C}{2(m_{1}+m_{2})}k^{2}a^{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( k_{max}=\pm \frac{\pi }{a} \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( \omega _{+}^{2}=2C/m_{1} \) \end_inset . \begin_inset Formula \( \omega _{-}^{2}=2C/m_{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Fonones: \series default \begin_inset Formula \( E=(n+1/2)\hbar \omega \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \vec{p}=\hbar \vec{k} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Scattering de un fonón: \begin_inset Formula \( \vec{k}'=\vec{k}+\vec{k}_{fon\acute{o}n}+\vec{G} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Energía total de los fonones: \begin_inset Formula \( U=\sum _{k}\sum _{p}\left\langle n_{k,p}\right\rangle \hbar \omega _{k,p} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Número medio de fonones: \begin_inset Formula \( \left\langle n\right\rangle =\frac{1}{e^{\hbar \omega /k_{B}T}-1} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( U=\sum _{p}\int d\omega D_{p}(\omega )\frac{\hbar \omega }{e^{\hbar \omega /k_{B}T}-1} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( C_{V}=\frac{\partial U}{\partial T} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Densidad de estados: \series default (1D) Un estado permitido por cada intervalo \begin_inset Formula \( \left( \frac{2\pi }{L}\right) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( D(\omega )=\frac{L}{\pi }\frac{dk}{d\omega }=\frac{dN}{d\omega } \) \end_inset \begin_inset Formula \( \bullet \) \end_inset (2D) 1 estado por área \begin_inset Formula \( \left( \frac{2\pi }{L_{x}}\right) \left( \frac{2\pi }{Ly}\right) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( D(\omega )=\frac{L^{2}}{2\pi }k\frac{dk}{d\omega } \) \end_inset \begin_inset Formula \( \bullet \) \end_inset (3D) 1 estado por volumen \begin_inset Formula \( \left( \frac{2\pi }{L_{x}}\right) \left( \frac{2\pi }{L_{y}}\right) \left( \frac{2\pi }{L_{z}}\right) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( D(\omega )=\frac{V}{2\pi ^{2}}k^{2}\frac{dk}{d\omega } \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Modelo de Debye: \series default Dispersion lineal \begin_inset Formula \( \omega =vk \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( D(\omega )=\frac{V\omega ^{2}}{2\pi ^{2}v^{3}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( N=\int _{0}^{\omega _{D}}D(\omega )d\omega \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset Freciencia de Debye (frecuencia máx.): \begin_inset Formula \( \omega _{D}^{3}=\frac{6\pi ^{2}v^{3}}{V}N \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( k_{D}=\omega _{D}/v \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Energía térmica (1 polarización): \begin_inset Formula \( U_{p}=\int d\omega D(\omega )f(\omega )E_{\omega } \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( U=U_{p}\times 3 \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( U=9Nk_{B}T\left( \frac{T}{\theta _{D}}\right) ^{3}\int _{0}^{x_{D}}dx\frac{x^{3}}{e^{x}-1} \) \end_inset con \begin_inset Formula \( x=\beta \hbar \omega \) \end_inset , \begin_inset Formula \( \theta _{D}=x_{D}T=\frac{\hbar }{k_{B}}v\left( \frac{6\pi ^{2}}{V}\right) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( C_{V}=9Nk_{B}\left( \frac{T}{\theta _{D}}\right) ^{3}\int _{0}^{x_{D}}dx\frac{x^{4}e^{x}}{(e^{x}-1)^{2}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Ley \begin_inset Formula \( T^{3} \) \end_inset de Debye: \series default i) Altas temperaturas: \begin_inset Formula \( k_{B}T\gg \hbar \omega \Rightarrow x\ll 1 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( U=3Nk_{B}T \) \end_inset , \begin_inset Formula \( C_{V}=3Nk_{B} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset ii) Bajas temperaturas: \begin_inset Formula \( k_{B}T\ll \hbar \omega \Rightarrow x\gg 1 \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( U=9Nk_{B}T^{4}\frac{\pi ^{4}}{15\theta _{D}^{3}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( C_{V}=\frac{12\pi ^{4}}{5}\frac{Nk_{B}}{\theta _{D}^{3}}T^{3} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Modelo de Einstein: \series default \begin_inset Formula \( U=3N\frac{\hbar \omega }{e^{\hbar \omega /k_{B}T}-1} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( C_{V}=\frac{3Nk_{B}(\hbar \omega /k_{B}T)^{2}}{(e^{\hbar \omega /k_{B}T}-1)^{2}}e^{\hbar \omega /k_{B}T} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset i) Altas temperaturas: \begin_inset Formula \( C_{V}\simeq 3Nk_{B} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset ii) Bajas temp.: \begin_inset Formula \( C_{V}\simeq 3Nk_{B}\left( \frac{\hbar \omega }{k_{B}T}\right) ^{3}e^{-\frac{\hbar \omega }{k_{B}T}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \theta _{E}=\frac{\hbar \omega _{E}}{k_{B}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Expansión térmica: \series default \begin_inset Formula \( \left\langle x\right\rangle =\frac{3g}{4c^{2}}k_{B}T \) \end_inset , con \begin_inset Formula \( U(x)=cx^{2}-gx^{3}-fx^{4} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Conductividad térmica: \series default \begin_inset Formula \( K=\frac{1}{3}Cvl \) \end_inset con \begin_inset Formula \( C=C_{V}/V \) \end_inset , \begin_inset Formula \( v= \) \end_inset velocidad media, y \begin_inset Formula \( l= \) \end_inset recorrido libre medio. \layout Section* Tema 5. Gas de electrones libres de Fermi. \layout Standard \align left \series bold Niveles de energía (1D): \series default \begin_inset Formula \( \psi _{n}=A\sin \frac{2\pi n}{L} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \epsilon _{n}=\frac{\hbar ^{2}}{2m}\left( \frac{n\pi }{L}\right) ^{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Energía de Fermi: \begin_inset Formula \( \epsilon _{F}=\frac{\hbar ^{2}}{2m}\left( \frac{N\pi }{2L}\right) ^{2} \) \end_inset , con \begin_inset Formula \( 2n_{F}=N \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Distribución de Fermi-Dirac: \begin_inset Formula \( f(E)=\frac{1}{e^{(\epsilon -\mu )/k_{B}T}-1} \) \end_inset . \series default A \series bold \begin_inset Formula \( T=0K\Rightarrow \mu =\epsilon _{F} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Gas de Electrones libres (3D): \series default \begin_inset Formula \( \psi _{k}(\vec{r})=e^{i\vec{k}\vec{r}} \) \end_inset , con \begin_inset Formula \( k_{x}=0,\pm 2\pi /L,\pm 4\pi /L... \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \epsilon _{k}=\frac{\hbar ^{2}k^{2}}{2m} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \vec{p}=\hbar \vec{k} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( k_{F}=\left( \frac{3\pi ^{2}N}{V}\right) ^{1/3} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Energía de Fermi: \begin_inset Formula \( \epsilon _{F}=\frac{\hbar ^{2}}{2m}k_{F} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Velocidad de Fermi: \begin_inset Formula \( v_{F}=\frac{\hbar }{m}\left( \frac{3\pi ^{2}N}{V}\right) ^{1/3} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Densidad de estados: \begin_inset Formula \( N(\epsilon )=\frac{V}{3\pi 2}\left( \frac{2m\epsilon }{\hbar ^{2}}\right) ^{3/2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( D(\epsilon )=\frac{dN}{d\epsilon }=\frac{V}{2\pi ^{2}}\left( \frac{2m}{\hbar ^{2}}\right) ^{3/2}\epsilon ^{1/2}=\frac{3N}{2\epsilon } \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Capacidad calorífica de un gas de electrones: \begin_inset Formula \( C_{e^{-}}=\frac{d}{dT}\left\langle U\right\rangle =\frac{d}{dT}\int _{0}^{\infty }d\epsilon \epsilon D(\epsilon )f(\epsilon ) \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( C_{e^{-}}\simeq \frac{1}{3}\pi ^{2}\frac{3N}{2\epsilon _{F}}k_{B}^{2}T \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset Capacidad calorífica experimental: \begin_inset Formula \( C=\gamma T \) \end_inset ( \begin_inset Formula \( e^{-} \) \end_inset libres) \begin_inset Formula \( +\alpha T^{3} \) \end_inset (Debye) \begin_inset Formula \( \bullet \) \end_inset \series bold Ley de Ohm: \series default \begin_inset Formula \( \vec{F}=m\frac{d\vec{v}}{dt}=\hbar \frac{dk}{dt}=-e(\vec{E}+\vec{v}\wedge \vec{B}) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Desplazamiento de la esfera de Fermi: \begin_inset Formula \( \delta \vec{k}=\frac{-e\vec{E}}{\hbar }t \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Densidad de corriente: \begin_inset Formula \( \vec{j}=nq\vec{v}=\sigma \vec{E} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Conductividad eléctrica: \begin_inset Formula \( \sigma =\frac{ne^{2}\tau }{m} \) \end_inset , con \begin_inset Formula \( \tau \equiv \) \end_inset tiempo medio entre choques. \begin_inset Formula \( \bullet \) \end_inset Resistividad eléctrica: \begin_inset Formula \( \rho =1/\sigma \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Recorrido libre medio: \begin_inset Formula \( l=v_{F}\tau \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Resisitividad experimental: \begin_inset Formula \( \rho =\rho _{fon\acute{o}n}+\rho _{defectos} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Movimiento en un CEM: \series default Ecuación de movimiento: \begin_inset Formula \( \hbar \left( \frac{d}{dt}+\frac{1}{\tau }\right) \delta \vec{k}=\vec{F} \) \end_inset tb: \begin_inset Formula \( m\left( \frac{d}{dt}+\frac{1}{\tau }\right) \vec{v}=-e(\vec{E}+\vec{v}\wedge \vec{B}) \) \end_inset . Soluciones: \begin_inset Formula \( v_{x}=-\frac{e\tau }{m}E_{x}-\omega _{c}\tau v_{y} \) \end_inset , \begin_inset Formula \( v_{y}=-\frac{e\tau }{m}E_{y}-\omega _{c}\tau v_{x} \) \end_inset , \begin_inset Formula \( v_{z}=\frac{-e\tau }{m}E_{z} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Frecuencia de ciclotrón: \begin_inset Formula \( \omega _{c}=\frac{eB}{mc} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Efecto Hall: \series default Campo Hall: \begin_inset Formula \( E_{y}=-\omega _{c}\tau E_{x}=-\frac{eB\tau }{m}E_{x} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Coeficiente Hall: \begin_inset Formula \( R_{H}=\frac{E_{y}}{j_{x}B}=-\frac{1}{ne} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Resistencia Hall: \begin_inset Formula \( \rho _{H}=-\frac{B}{ne}=\frac{E_{y}}{j_{x}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Conductividad térmica en metales: \begin_inset Formula \( K=\frac{\pi ^{2}nk_{B}T\tau }{3m} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series default Número de Lorenz: \begin_inset Formula \( \frac{k}{\sigma }=\frac{\pi ^{2}}{3}\left( \frac{k_{B}}{e}\right) ^{2}T \) \end_inset , \begin_inset Formula \( L=\frac{k}{\sigma T}=2.44\times 10^{-8}\frac{J^{2}}{K^{2}\cdot C^{2}} \) \end_inset \layout Section* Tema 6. Bandas de energía. \layout Standard \align left \series bold Potencial periódico. Modelo de \begin_inset Formula \( e^{-} \) \end_inset cuasilibres. \series default Gap en \begin_inset Formula \( k=\pm \pi /a=\pm \frac{1G}{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Ondas en 1ª zona de Brillouin: \begin_inset Formula \( \psi _{+}=2\cos \frac{\pi x}{a} \) \end_inset , \begin_inset Formula \( \psi _{-}=2i\sin \frac{\pi x}{a} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Magnitud del gap de Energía: \begin_inset Formula \( U(x)=U\cos \frac{2\pi x}{a} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( E_{g}=\int _{0}^{1}dxU(x)\left\{ \left| \psi _{+}\right| ^{2}-\left| \psi _{-}\right| ^{2}\right\} =U \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Funciones de Bloch. \series default \begin_inset Formula \( \psi _{\vec{k}}(\vec{r})=u_{\vec{k}}(\vec{r})e^{i\vec{k}\vec{r}} \) \end_inset con \begin_inset Formula \( u_{\vec{k}}(\vec{r})=u_{\vec{k}}(\vec{r}+\vec{T}) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Modelo de Kronig-Penney. \series default Potencial periódico (PP): función escalón. Condiciones de contorno periódicas. Aprox: funciones \begin_inset Formula \( \delta \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Ecuación de ondas del \begin_inset Formula \( e^{-} \) \end_inset en un PP. \series default Ec. de Schrödinger: \begin_inset Formula \( \left[ \frac{p^{2}}{2m}+U(x)\right] \psi (x)=\epsilon \psi (x) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( U(x)=\sum _{G}U_{G}e^{iGx} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \psi (x)=\sum _{k}C(k)e^{ikx} \) \end_inset con \begin_inset Formula \( k=\frac{2\pi n}{L} \) \end_inset , \begin_inset Formula \( L \) \end_inset longitud del cristal. \begin_inset Formula \( \bullet \) \end_inset Ecuación de ondas (Fourier) (Ecuación central): \begin_inset Formula \( (\lambda _{k}-\epsilon )C(k)+\sum _{G}U_{G}C(k-G)=0 \) \end_inset con \begin_inset Formula \( \lambda _{k}=\hbar ^{2}k^{2}/2m \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \psi _{k}(x)=\sum _{G}C(k-G)e^{i(k-g)x} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( u_{k}(x)\equiv \sum _{G}C(k-G)e^{-iGx} \) \end_inset Invariante bajo traslaciones de cristal \begin_inset Formula \( T \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \vec{k}\equiv \) \end_inset Momento cristalino del \begin_inset Formula \( e^{-} \) \end_inset : \begin_inset Formula \( \vec{k}+\vec{q}=\vec{k}'+\vec{G} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Energía del \begin_inset Formula \( e^{-} \) \end_inset libre: \begin_inset Formula \( \epsilon (k_{x},k_{y},k_{z})=(\hbar ^{2}/2m)(\vec{k}+\vec{G})^{2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Solución aprox. en la frontera: \begin_inset Formula \( k=\pm \frac{1}{2}G \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( \epsilon =\lambda \pm U=\frac{\hbar ^{2}}{2m}(\frac{1}{2}G)^{2}\pm U \) \end_inset \begin_inset Formula \( \Rightarrow \) \end_inset \begin_inset Formula \( \epsilon =\frac{1}{2}(\lambda _{k-G}+\lambda _{k})\pm \left[ \frac{1}{4}(\lambda _{k-G}-\lambda _{k})^{2}+U^{2}\right] ^{1/2} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Nº de orbitales en una banda. \begin_inset Formula \( 2N \) \end_inset \series default con \begin_inset Formula \( N= \) \end_inset nº de celdas primitivas de parámetro \begin_inset Formula \( a \) \end_inset . \layout Section* Tema 7. Cristales semiconductores. \layout Standard \align left \series bold Gap. \series default Transiciones directas: \begin_inset Formula \( E_{g}=\hbar \omega _{g} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Transiciones indirectas: \begin_inset Formula \( E_{g}=\hbar \omega -\hbar \Omega \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \series bold Ecuaciones de movimiento. \series default Velodidad de grupo: \begin_inset Formula \( v_{g}=\frac{d\omega }{dk}=\frac{1}{\hbar }\frac{d\epsilon }{dk} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \vec{v}=\frac{1}{\hbar }\nabla _{\vec{k}}\epsilon (\vec{k}) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Fuerza externa aplicada sobre el \begin_inset Formula \( e^{-} \) \end_inset : \begin_inset Formula \( \vec{F}=\hbar \frac{d\vec{k}}{dt} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Campo magnético: \begin_inset Formula \( \hbar \frac{d\vec{k}}{dt}=-e\vec{v}\times \vec{B} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset huecos: \begin_inset Formula \( \vec{k}_{h}=-\vec{K}_{e} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \epsilon _{h}(\vec{k}_{h})=-\epsilon _{e}(\vec{k}_{e}) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \vec{v}_{h}=\vec{v}_{e} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( m_{h}=-m_{e} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \hbar \frac{d\vec{k}_{h}}{dt}=e(\vec{E}+\vec{v}_{h}\times \vec{B}) \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Masa efectiva: \begin_inset Formula \( \frac{1}{m^{*}}=\frac{1}{\hbar ^{2}}\frac{d^{2}\vec{\epsilon }}{dk^{2}} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset \begin_inset Formula \( \left( \frac{1}{m^{*}}\right) _{\mu \nu }=\frac{1}{\hbar ^{2}}\frac{d^{2}\vec{\epsilon }_{k}}{dk_{\mu }dk_{\nu }} \) \end_inset \begin_inset Formula \( \bullet \) \end_inset Frecuencia de ciclotrón: \begin_inset Formula \( \omega _{c}=\frac{eB}{m^{*}} \) \end_inset \the_end