Knowledge (XXG)

Empty lattice approximation

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1352: 1340: 1328: 893: 225: 1312: 1300: 1288: 735: 248:, it is possible to calculate the band structure analytically by substituting the values for the potential, the lattice spacing and the size of potential well. For two and three-dimensional problems it is more difficult to calculate a band structure based on a similar model with a few parameters accurately. Nevertheless, the properties of the band structure can easily be approximated in most regions by 883:
In three-dimensional space the Brillouin zone boundaries are planes. The dispersion relations show conics of the free-electron energy dispersion parabolas for all possible reciprocal lattice vectors. This results in a very complicated set intersecting of curves when the dispersion relations are
216:. The energy of the electrons in the "empty lattice" is the same as the energy of free electrons. The model is useful because it clearly illustrates a number of the sometimes very complex features of energy dispersion relations in solids which are fundamental to all electronic band structures. 742:
Though the lattice cells are not spherically symmetric, the dispersion relation still has spherical symmetry from the point of view of a fixed central point in a reciprocal lattice cell if the dispersion relation is extended outside the central Brillouin zone. The
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The periodic potential of the lattice in this free electron model must be weak because otherwise the electrons wouldn't be free. The strength of the scattering mainly depends on the geometry and topology of the system. Topologically defined parameters, like
366: 208:(close to constant). One may also consider an empty irregular lattice, in which the potential is not even periodic. The empty lattice approximation describes a number of properties of energy dispersion relations of non-interacting 244:. For 1-, 2- and 3-dimensional spaces potential wells do always scatter waves, no matter how small their potentials are, what their signs are or how limited their sizes are. For a particle in a one-dimensional lattice, like the 878: 1181: 486:
that determine the bands in an energy interval is limited to two when the energy rises. In two and three dimensional lattices the number of reciprocal lattice vectors that determine the free electron bands
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calculated because there is a large number of possible angles between evaluation trajectories, first and higher order Brillouin zone boundaries and dispersion parabola intersection cones.
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In theory the lattice is infinitely large, so a weak periodic scattering potential will eventually be strong enough to reflect the wave. The scattering process results in the well known
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The figure on the right shows the dispersion relation for three periods in reciprocal space of a one-dimensional lattice with lattice cells of length
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increases more rapidly when the length of the wave vector increases and the energy rises. This is because the number of reciprocal lattice vectors
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in a three-dimensional lattice will be the same as in the case of the absence of a lattice. For the three-dimensional case the density of states
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between the reciprocal lattice vectors in the Hamiltonian almost go to zero. As a result, the magnitude of the band gap
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strongly reduces the electric field of the ions in the solid. The electrostatic potential is expressed as
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far outside the first Brillouin zone are still reflected back into the first Brillouin zone. See the
22: 209: 87: 30: 903: 224: 401: 264: 361:{\displaystyle E_{n}(\mathbf {k} )={\frac {\hbar ^{2}(\mathbf {k} +\mathbf {G} _{n})^{2}}{2m}}} 1394: 1042: 744: 602: 260: 213: 1441: 949: 151: 1429: 892: 1436: 1424: 75: 263:. This is the origin of the periodicity of the dispersion relation and the division of 256: 241: 16:
Theoretical electronic band structure model in which the potential is periodic and weak
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Physics Lecture Notes. P.Dirac, Feynman, R.,1968. Internet, Amazon,25.03.2014.
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in Brillouin zones. The periodic energy dispersion relation is expressed as:
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is a screening parameter that determines the range of the potential. The
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In a one-dimensional lattice the number of reciprocal lattice vectors
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crystallize in three kinds of crystal structures: the BCC and FCC
1266: 941: 891: 733: 1176:{\displaystyle U_{\mathbf {G} }={\frac {4\pi Ze}{q^{2}+G^{2}}}} 240:, depend on the magnitude of the potential and the size of the 693:
in reciprocal space and the slope of the dispersion relation
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collapses and the empty lattice approximation is obtained.
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DoITPoMS Teaching and Learning Package- "Brillouin Zones"
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Brillouin Zone simple lattice diagrams by Thayer Watkins
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is the distance to the nucleus of the embedded ion and
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Figure 3: Free-electron DOS in 3-dimensional k-space
1249: 1207: 1175: 1097: 1066: 1010: 914: 872: 777: 723: 685: 638: 593: 546: 517: 478: 434: 392: 360: 646:depends on the number of states in an interval 228:Free electron bands in a one dimensional lattice 1430:Brillouin Zone 3d lattice diagrams by Technion. 1357:Free electron bands in a HCP crystal structure 1345:Free electron bands in a FCC crystal structure 1333:Free electron bands in a BCC crystal structure 259:of electrons by the periodic potential of the 1186:When the values of the off-diagonal elements 926:section for sites with examples and figures. 173: 8: 1261:The electron bands of common metal crystals 1011:{\displaystyle V(r)={\frac {Ze}{r}}e^{-qr}} 80:Multi-configurational self-consistent field 453:The energy bands and the density of states 180: 166: 18: 1242: 1235: 1234: 1225: 1220: 1198: 1197: 1191: 1164: 1151: 1130: 1120: 1119: 1113: 1087: 1079: 1057: 1056: 1050: 996: 977: 960: 907: 905: 855: 850: 839: 825: 799: 793: 758: 752: 713: 704: 698: 675: 664: 656: 651: 610: 583: 572: 564: 559: 538: 533: 530: 507: 498: 492: 470: 465: 462: 424: 415: 409: 384: 379: 376: 341: 331: 326: 317: 308: 301: 290: 281: 275: 888:Second, third and higher Brillouin zones 223: 102:Time-dependent density functional theory 64:Semi-empirical quantum chemistry methods 1370: 1283: 305: 123: 93: 51: 29: 21: 114:Linearized augmented-plane-wave method 110:Orbital-free density functional theory 7: 1265:Apart from a few exotic exceptions, 1390:Introduction to Solid State Physics 1250:{\displaystyle 2|U_{\mathbf {G} }|} 923: 778:{\displaystyle D_{3}\left(E\right)} 724:{\displaystyle E_{n}(\mathbf {k} )} 518:{\displaystyle E_{n}(\mathbf {k} )} 435:{\displaystyle E_{n}(\mathbf {k} )} 84:Quantum chemistry composite methods 68:Møller–Plesset perturbation theory 14: 1350: 1338: 1326: 1310: 1298: 1286: 1236: 1208:{\displaystyle U_{\mathbf {G} }} 1199: 1121: 1088: 1067:{\displaystyle U_{\mathbf {G} }} 1058: 908: 714: 676: 665: 657: 584: 573: 565: 547:{\displaystyle \mathbf {G} _{n}} 534: 508: 479:{\displaystyle \mathbf {G} _{n}} 466: 425: 393:{\displaystyle \mathbf {G} _{n}} 380: 327: 318: 291: 200:model in which the potential is 1098:{\displaystyle V(\mathbf {r} )} 1033:is the elementary unit charge, 118:Projector augmented wave method 1243: 1226: 1092: 1084: 971: 965: 930:The nearly free electron model 718: 710: 680: 653: 633: 612: 588: 561: 512: 504: 429: 421: 338: 314: 295: 287: 1: 156:Korringa–Kohn–Rostoker method 1074:, of the lattice potential, 915:{\displaystyle \mathbf {k} } 404:vectors to which the bands 194:empty lattice approximation 148:Empty lattice approximation 1478: 1462:Electronic band structures 936:Nearly free electron model 933: 220:Scattering and periodicity 132:Nearly free electron model 46:Modern valence bond theory 198:electronic band structure 125:Electronic band structure 95:Density functional theory 72:Configuration interaction 1271:cubic crystal structures 554:that lie in an interval 140:Muffin-tin approximation 53:Molecular orbital theory 42:Generalized valence bond 1387:C. Kittel (1953–1976). 1305:Face-centered cubic (F) 1293:Body-centered cubic (I) 144:k·p perturbation theory 1317:Hexagonal close-packed 1251: 1209: 1177: 1099: 1068: 1012: 916: 897: 874: 779: 739: 725: 687: 640: 605:in an energy interval 595: 548: 519: 480: 436: 394: 362: 229: 38:Coulson–Fischer theory 1252: 1210: 1178: 1100: 1069: 1013: 917: 895: 875: 780: 737: 726: 688: 641: 596: 549: 520: 481: 437: 395: 363: 227: 1393:. Wiley & Sons. 1281:crystal structure. 1219: 1190: 1112: 1078: 1049: 959: 904: 792: 751: 697: 650: 609: 558: 529: 491: 461: 408: 375: 274: 250:perturbation methods 212:that move through a 23:Electronic structure 860: 246:Kronig–Penney model 88:Quantum Monte Carlo 60:Hartree–Fock method 31:Valence bond theory 1435:2006-12-05 at the 1423:2006-09-14 at the 1247: 1205: 1173: 1105:, is expressed as 1095: 1064: 1008: 912: 898: 896:FCC Brillouin zone 870: 846: 775: 740: 721: 683: 636: 591: 544: 515: 476: 432: 402:reciprocal lattice 390: 358: 230: 106:Thomas–Fermi model 1400:978-0-471-49024-1 1171: 1043:Fourier transform 990: 866: 862: 861: 745:density of states 603:density of states 356: 261:crystal structure 257:Bragg reflections 196:is a theoretical 190: 189: 1469: 1405: 1404: 1384: 1378: 1375: 1354: 1342: 1330: 1314: 1302: 1290: 1256: 1254: 1253: 1248: 1246: 1241: 1240: 1239: 1229: 1214: 1212: 1211: 1206: 1204: 1203: 1202: 1182: 1180: 1179: 1174: 1172: 1170: 1169: 1168: 1156: 1155: 1145: 1131: 1126: 1125: 1124: 1104: 1102: 1101: 1096: 1091: 1073: 1071: 1070: 1065: 1063: 1062: 1061: 1017: 1015: 1014: 1009: 1007: 1006: 991: 986: 978: 950:screening effect 921: 919: 918: 913: 911: 879: 877: 876: 871: 864: 863: 859: 854: 845: 844: 843: 827: 826: 815: 804: 803: 784: 782: 781: 776: 774: 763: 762: 730: 728: 727: 722: 717: 709: 708: 692: 690: 689: 686:{\displaystyle } 684: 679: 668: 660: 645: 643: 642: 639:{\displaystyle } 637: 600: 598: 597: 594:{\displaystyle } 592: 587: 576: 568: 553: 551: 550: 545: 543: 542: 537: 524: 522: 521: 516: 511: 503: 502: 485: 483: 482: 477: 475: 474: 469: 441: 439: 438: 433: 428: 420: 419: 399: 397: 396: 391: 389: 388: 383: 367: 365: 364: 359: 357: 355: 347: 346: 345: 336: 335: 330: 321: 313: 312: 302: 294: 286: 285: 182: 175: 168: 152:GW approximation 19: 1477: 1476: 1472: 1471: 1470: 1468: 1467: 1466: 1447: 1446: 1437:Wayback Machine 1425:Wayback Machine 1414: 1409: 1408: 1401: 1386: 1385: 1381: 1376: 1372: 1367: 1362: 1361: 1360: 1359: 1358: 1355: 1347: 1346: 1343: 1335: 1334: 1331: 1318: 1315: 1306: 1303: 1294: 1291: 1263: 1230: 1217: 1216: 1193: 1188: 1187: 1160: 1147: 1146: 1132: 1115: 1110: 1109: 1076: 1075: 1052: 1047: 1046: 992: 979: 957: 956: 938: 932: 902: 901: 890: 835: 828: 805: 795: 790: 789: 764: 754: 749: 748: 700: 695: 694: 648: 647: 607: 606: 601:increases. The 556: 555: 532: 527: 526: 494: 489: 488: 464: 459: 458: 455: 411: 406: 405: 378: 373: 372: 348: 337: 325: 304: 303: 277: 272: 271: 222: 214:crystal lattice 186: 154: 150: 146: 142: 138: 134: 116: 112: 108: 104: 86: 82: 78: 76:Coupled cluster 74: 70: 66: 62: 44: 40: 17: 12: 11: 5: 1475: 1473: 1465: 1464: 1459: 1457:Quantum models 1449: 1448: 1445: 1444: 1439: 1427: 1413: 1412:External links 1410: 1407: 1406: 1399: 1379: 1369: 1368: 1366: 1363: 1356: 1349: 1348: 1344: 1337: 1336: 1332: 1325: 1324: 1323: 1322: 1321: 1320: 1319: 1316: 1309: 1307: 1304: 1297: 1295: 1292: 1285: 1262: 1259: 1245: 1238: 1233: 1228: 1224: 1201: 1196: 1184: 1183: 1167: 1163: 1159: 1154: 1150: 1144: 1141: 1138: 1135: 1129: 1123: 1118: 1094: 1090: 1086: 1083: 1060: 1055: 1019: 1018: 1005: 1002: 999: 995: 989: 985: 982: 976: 973: 970: 967: 964: 934:Main article: 931: 928: 924:external links 910: 889: 886: 881: 880: 869: 858: 853: 849: 842: 838: 834: 831: 824: 821: 818: 814: 811: 808: 802: 798: 773: 770: 767: 761: 757: 720: 716: 712: 707: 703: 682: 678: 674: 671: 667: 663: 659: 655: 635: 632: 629: 626: 623: 620: 617: 614: 590: 586: 582: 579: 575: 571: 567: 563: 541: 536: 514: 510: 506: 501: 497: 473: 468: 454: 451: 431: 427: 423: 418: 414: 387: 382: 369: 368: 354: 351: 344: 340: 334: 329: 324: 320: 316: 311: 307: 300: 297: 293: 289: 284: 280: 242:potential well 238:cross sections 221: 218: 210:free electrons 188: 187: 185: 184: 177: 170: 162: 159: 158: 128: 127: 121: 120: 98: 97: 91: 90: 56: 55: 49: 48: 34: 33: 27: 26: 15: 13: 10: 9: 6: 4: 3: 2: 1474: 1463: 1460: 1458: 1455: 1454: 1452: 1443: 1440: 1438: 1434: 1431: 1428: 1426: 1422: 1419: 1416: 1415: 1411: 1402: 1396: 1392: 1391: 1383: 1380: 1374: 1371: 1364: 1353: 1341: 1329: 1313: 1308: 1301: 1296: 1289: 1284: 1282: 1280: 1277:close-packed 1276: 1272: 1268: 1260: 1258: 1231: 1222: 1194: 1165: 1161: 1157: 1152: 1148: 1142: 1139: 1136: 1133: 1127: 1116: 1108: 1107: 1106: 1081: 1053: 1044: 1040: 1036: 1032: 1028: 1027:atomic number 1024: 1003: 1000: 997: 993: 987: 983: 980: 974: 968: 962: 955: 954: 953: 951: 947: 943: 942:simple metals 937: 929: 927: 925: 894: 887: 885: 867: 856: 851: 847: 840: 836: 832: 829: 822: 819: 816: 812: 809: 806: 800: 796: 788: 787: 786: 771: 768: 765: 759: 755: 746: 736: 732: 705: 701: 672: 669: 661: 630: 627: 624: 621: 618: 615: 604: 580: 577: 569: 539: 499: 495: 471: 452: 450: 448: 443: 416: 412: 403: 385: 352: 349: 342: 332: 322: 309: 298: 282: 278: 270: 269: 268: 266: 262: 258: 253: 251: 247: 243: 239: 236: 226: 219: 217: 215: 211: 207: 203: 199: 195: 183: 178: 176: 171: 169: 164: 163: 161: 160: 157: 153: 149: 145: 141: 137: 136:Tight binding 133: 130: 129: 126: 122: 119: 115: 111: 107: 103: 100: 99: 96: 92: 89: 85: 81: 77: 73: 69: 65: 61: 58: 57: 54: 50: 47: 43: 39: 36: 35: 32: 28: 24: 20: 1388: 1382: 1373: 1264: 1185: 1038: 1034: 1030: 1022: 1020: 939: 899: 882: 741: 456: 446: 444: 370: 254: 231: 205: 201: 193: 191: 147: 1451:Categories 1365:References 235:scattering 1275:hexagonal 1137:π 998:− 946:aluminium 833:− 823:π 306:ℏ 1433:Archived 1421:Archived 1273:and the 940:In most 442:belong. 400:are the 202:periodic 1025:is the 944:, like 265:k-space 25:methods 1397:  1267:metals 1021:where 948:, the 865:  1395:ISBN 785:is; 371:The 206:weak 204:and 192:The 1279:HCP 1453:: 1045:, 1029:, 731:. 449:. 252:. 1403:. 1244:| 1237:G 1232:U 1227:| 1223:2 1200:G 1195:U 1166:2 1162:G 1158:+ 1153:2 1149:q 1143:e 1140:Z 1134:4 1128:= 1122:G 1117:U 1093:) 1089:r 1085:( 1082:V 1059:G 1054:U 1039:q 1035:r 1031:e 1023:Z 1004:r 1001:q 994:e 988:r 984:e 981:Z 975:= 972:) 969:r 966:( 963:V 909:k 868:. 857:3 852:k 848:c 841:0 837:E 830:E 820:2 817:= 813:) 810:E 807:( 801:3 797:D 772:) 769:E 766:( 760:3 756:D 719:) 715:k 711:( 706:n 702:E 681:] 677:k 673:d 670:+ 666:k 662:, 658:k 654:[ 634:] 631:E 628:d 625:+ 622:E 619:, 616:E 613:[ 589:] 585:k 581:d 578:+ 574:k 570:, 566:k 562:[ 540:n 535:G 513:) 509:k 505:( 500:n 496:E 472:n 467:G 447:a 430:) 426:k 422:( 417:n 413:E 386:n 381:G 353:m 350:2 343:2 339:) 333:n 328:G 323:+ 319:k 315:( 310:2 299:= 296:) 292:k 288:( 283:n 279:E 181:e 174:t 167:v

Index

Electronic structure
Valence bond theory
Coulson–Fischer theory
Generalized valence bond
Modern valence bond theory
Molecular orbital theory
Hartree–Fock method
Semi-empirical quantum chemistry methods
Møller–Plesset perturbation theory
Configuration interaction
Coupled cluster
Multi-configurational self-consistent field
Quantum chemistry composite methods
Quantum Monte Carlo
Density functional theory
Time-dependent density functional theory
Thomas–Fermi model
Orbital-free density functional theory
Linearized augmented-plane-wave method
Projector augmented wave method
Electronic band structure
Nearly free electron model
Tight binding
Muffin-tin approximation
k·p perturbation theory
Empty lattice approximation
GW approximation
Korringa–Kohn–Rostoker method
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