Preface
ⅠBasic Models
1 Electron Interactions in Solids
2 Spin Exchange
The Hubbard Model and Its Descendants
Ⅱ Wave Functions and Correlations
4 Ground States of the Hubbard Model
5 Ground States of the Heisenberg Model
6 Disorder in Low Dimensions
7 Spin Representations
8 Variational Wave Functions and Parent Hamiltonians
From Ground States to Excitations
Ⅲ Path Integral Approximations
10 The Spin Path Integral
11 Spin Wave Theory
12 The Continuum Approximation
13 Nonlinear Sigma Model: Weak Coupling
14 The Nonlinear Sigma Model: Large N
15 Quantum Antlferromagnets: Continuum Results
16 SU(N) Helsenberg Models
17 The Large N Expansion
18 Schwinger Bosons Mean Field Theory
19 The Semiclassical Theory of the t - J Model
Ⅳ Mathematical Appendices
Appendix A Second Quantigation
Appendix B Linear Response and Generating Functlonals
Appendix C Bose and Fermi Coherent States
Appendix D Coherent State Path Integrals
Appendix E The Method of Steepest Descents
Index