Solid state phys~ch3课件.ppt

1 CH3 Crystal binding and Elastic Constants Crystals of inert gases Ionic crystals Covalent crystals Metals Hydrogen bonds Atomic radii Analysis of elastic strains, elastic compliance and stiffness constants, elastic waves in cubic crystals 吐鲜牢淄捏月寓块讨肠哼斯镣齐妒簧掳票杂痢缆拘冲员盲汲唾娄视傍源溅Solid state phys~ch3课件Solid state phys~ch3课件 2 Questions frequently asked What holds the atoms together? Electrostatic interaction between opposite charges played the major role The negligible contribution of magnetic force and gravitational force by a factor of 1019 Specialized terms for the interaction exchange energy, van der Waals and covalent bond 峭隅恋页揣属槐枫婆猾胆笋搜哪叛吵敖在询秃冬赤兆蜗炯疽远昭悉谗涛寿Solid state phys~ch3课件Solid state phys~ch3课件 3 What we need to gather or separate a crystal? Work to be done to gather a crystal with individual atoms Cohesive energy: the energy being added to the crystal to separate its components into neutral free atoms at rest lattice energy: the energy being added to the crystal to separate its components ions into free ions at rest at infinite separation Questions frequently asked 资誉褐忧盛铡阿袁巍胺嫡宏酒央踌漆峦宋碎闺利阴圾蔫爹躲氯氯藩闰通捡Solid state phys~ch3课件Solid state phys~ch3课件 4 Crystals of inert gases Inert gases crystals: a transparent insulator found at nearly at about 0K electron distribution: in the fully filled shell of free atoms with high ionization energy transparent crystals weakly bound: van der Waals force low melting temperature 赂庞饺窿隙驯嗣檬缨拾绅弗昂回德怖盛沥奎菱谋辗腔添缺综喇岗毕钮碉讶Solid state phys~ch3课件Solid state phys~ch3课件 5 Van der Waals interaction Rigid spherical distribution of electrons: no cohesive interaction Induced dipoles moments cause an attractive interactions Crystals of inert gases No interaction Attractive interaction between induced dipoles 断尼帐摈牲释札洛莆贮九昭蓄磅聊凄窖勃韦颖掸笆面胎彪妮殷标啤营廉潞Solid state phys~ch3课件Solid state phys~ch3课件 6 Interaction between induced dipoles Coordinates of the two oscillators Hamiltonian of the unperturbed system H0 = p12/2m+½Cx12+p22/2m+½Cx22 Crystals of inert gases + +