{ "metadata": { "name": "", "signature": "sha256:fde95e6d9c736121aaabaa0d5609f06ddf07df078e4e974cfe128a5769da216f" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "17: Statistics and band theory of solids" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example number 17.1, Page number 23" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#importing modules\n", "import math\n", "from __future__ import division\n", "\n", "#Variable declaration\n", "rhoCu=8.96*10**3; #density of Cu(kg/m**3)\n", "awCu=63.55; #atomic weight of Cu\n", "nfCu=1*10**3; #number of free electrons per Cu atom\n", "rhoZn=7.14*10**3; #density of Zn(kg/m**3)\n", "awZn=65.38; #atomic weight of Zn\n", "nfZn=2*10**3; #number of free electrons per Zn atom\n", "rhoAl=2.7*10**3; #density of Al(kg/m**3)\n", "awAl=27; #atomic weight of Al\n", "nfAl=3*10**3; #number of free electrons per Al atom\n", "N=6.022*10**23; #avagadro constant\n", "h=6.626*10**-34; #planck's constant\n", "me=9.1*10**-31; #mass of electron(kg)\n", "e=1.6*10**-19; #electron charge(c)\n", "\n", "#Calculation\n", "nCu=rhoCu*N*nfCu/awCu; #concentration of electrons in Cu(per m**3)\n", "EF0Cu=(h**2/(8*me))*(3*nCu/math.pi)**(2/3); #fermi energy of Cu at 0K(J)\n", "EF0Cu=EF0Cu/e; #fermi energy of Cu at 0K(eV)\n", "nZn=rhoZn*N*nfZn/awZn; #concentration of electrons in Zn(per m**3)\n", "EF0Zn=(h**2/(8*me))*(3*nZn/math.pi)**(2/3); #fermi energy of Zn at 0K(J)\n", "EF0Zn=EF0Zn/e; #fermi energy of Zn at 0K(eV)\n", "nAl=rhoAl*N*nfAl/awAl; #concentration of electrons in Al(per m**3)\n", "EF0Al=(h**2/(8*me))*(3*nAl/math.pi)**(2/3); #fermi energy of Al at 0K(J)\n", "EF0Al=EF0Al/e; #fermi energy of Al at 0K(eV)\n", "\n", "#Result\n", "print \"fermi energy of Cu at 0K is\",round(EF0Cu,4),\"eV\"\n", "print \"fermi energy of Zn at 0K is\",round(EF0Zn,2),\"eV\"\n", "print \"fermi energy of Al at 0K is\",round(EF0Al,2),\"eV\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "fermi energy of Cu at 0K is 7.0608 eV\n", "fermi energy of Zn at 0K is 9.45 eV\n", "fermi energy of Al at 0K is 11.68 eV\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example number 17.2, Page number 25" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#importing modules\n", "import math\n", "from __future__ import division\n", "\n", "#Variable declaration\n", "nCu=8.4905*10**28; #concentration of electrons in Cu(per m**3)\n", "h=6.626*10**-34; #planck's constant\n", "me=9.1*10**-31; #mass of electron(kg)\n", "gama=6.82*10**27;\n", "\n", "#Calculation\n", "EF0=(h**2/(8*me))*(3*nCu/math.pi)**(2/3); #fermi energy of Cu at 0K(J)\n", "EF=EF0/e; #fermi energy of Cu at 0K(eV)\n", "DE=(gama/2)*math.sqrt(EF); #density of states for Cu at fermi level(per m**3)\n", "\n", "#Result\n", "print \"density of states for Cu at fermi level is\",int(DE/10**27),\"*10**27 per m**3\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "density of states for Cu at fermi level is 9 *10**27 per m**3\n" ] } ], "prompt_number": 4 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example number 17.3, Page number 26" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#importing modules\n", "import math\n", "from __future__ import division\n", "\n", "#Variable declaration\n", "rhoNi=69*10**-9; #resistivity of Ni(ohm m)\n", "rhoCr=129*10**-9; #resistivity of Cr(ohm m)\n", "rho=1120*10**-9; #resistivity(ohm m) \n", "X=0.8; \n", "\n", "#Calculation\n", "C=rho/(X*(1-X)); #Nordheim's coefficient(ohm m)\n", "\n", "#Result\n", "print \"Nordheim's coefficient is\",C,\"ohm m\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Nordheim's coefficient is 7e-06 ohm m\n" ] } ], "prompt_number": 5 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example number 17.4, Page number 26" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#importing modules\n", "import math\n", "from __future__ import division\n", "\n", "#Variable declaration\n", "rho=2.7*10**3; #density of Al(kg/m**3)\n", "M=27; #atomic weight of Al \n", "tow_r=10**-14; #relaxation time(s)\n", "e=1.6*10**-19; #charge of electron(c) \n", "NA=6.022*10**23; #avagadro constant\n", "m=9.1*10**-31; #mass of electron(kg)\n", "f=3*10**3; #number of free electrons per atom\n", "\n", "#Calculation\n", "n=rho*NA*f/M; #number of electrons available per m**3\n", "sigma=n*e**2*tow_r/m; #conductivity of Al(ohm m) \n", "\n", "#Result\n", "print \"conductivity of Al is\",round(sigma/10**7,4),\"*10**7 ohm m\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "conductivity of Al is 5.0823 *10**7 ohm m\n" ] } ], "prompt_number": 7 } ], "metadata": {} } ] }