复旦量子力学讲义——qm2_chapter21课件.ppt

Chapter 2Many Body Problem §2.1 Second quantization The identical particles cannot be distinguished §2.1 Second quantization The essence of the identical principle is that the state of a system should be described in terms of the particle number in a certain quantum state and the many-body problem should be discussed in the particle number representation instead of the original coordinate representation §2.1 Second quantization We need to introduce the creation and the annihilation operators to deal with various problem in the many-body system §2.1 Second quantization Bose system §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization Discussions The wave function is already symmetric nk is the particle number operator of k state §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization For Fermions §2.1 Second quantization §2.1 Second quantization §2.1 Second quantization §2.2 Hartree-Fork mean field approximation Key: two-body problem ?“one-body problem” + “mean field” Example: Free electron gas in the metal §2.2 Hartree-Fork mean field approximation §2.2 Hartree-Fork mean field approximation §2.2 Hartree-Fork mean field approximation §2.2 Hartree-Fork mean field approximation §2.2 Hartree-Fork mean field approximation §2.2 Hartree-Fork mean field approximation §2.2 Hartree-Fork mean field approximation §2.2 Hartree-Fork mean field approximation Spin effect §2.2 Hartree-Fork mean field approximation §2.2 Hartree-Fork mean field approximation §2.2 Hartree-Fork mean field approximation §2.3 Superconductive theory §2.3 Superconductive theory Frohlisch Hamiltonian: e-p-e interaction