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  2. Density of states - Wikipedia

    en.wikipedia.org/wiki/Density_of_states

    The density of states related to volume V and N countable energy levels is defined as: = = (()). Because the smallest allowed change of momentum for a particle in a box of dimension and length is () = (/), the volume-related density of states for continuous energy levels is obtained in the limit as ():= (()), Here, is the spatial dimension of the considered system and the wave vector.

  3. Van Hove singularity - Wikipedia

    en.wikipedia.org/wiki/Van_Hove_singularity

    The density of states which appears in the Fermi's Golden Rule expression is then the joint density of states, which is the number of electronic states in the conduction and valence bands that are separated by a given photon energy.

  4. Density matrix - Wikipedia

    en.wikipedia.org/wiki/Density_matrix

    The density matrix is a representation of a linear operator called the density operator. The density matrix is obtained from the density operator by a choice of an orthonormal basis in the underlying space. [2] In practice, the terms density matrix and density operator are often used interchangeably.

  5. Fermi gas - Wikipedia

    en.wikipedia.org/wiki/Fermi_gas

    α = d for hyper-relativistic particles in a d-dimensional box. For such a power-law density of states, the grand potential integral evaluates exactly to: [12] (,,) = + (), where () is the complete Fermi–Dirac integral (related to the polylogarithm). From this grand potential and its derivatives, all thermodynamic quantities of interest can ...

  6. Degenerate energy levels - Wikipedia

    en.wikipedia.org/wiki/Degenerate_energy_levels

    Two-dimensional quantum systems exist in all three states of matter and much of the variety seen in three dimensional matter can be created in two dimensions. Real two-dimensional materials are made of monoatomic layers on the surface of solids. Some examples of two-dimensional electron systems achieved experimentally include MOSFET, two ...

  7. Quantum well - Wikipedia

    en.wikipedia.org/wiki/Quantum_well

    Because of their quasi-two-dimensional nature, electrons in quantum wells have a density of states as a function of energy that has distinct steps, versus a smooth square root dependence that is found in bulk materials. Additionally, the effective mass of holes in the valence band is changed to more closely match that of electrons in the ...

  8. Purity (quantum mechanics) - Wikipedia

    en.wikipedia.org/wiki/Purity_(quantum_mechanics)

    The IPR basically takes the full information about a quantum system (the wave function; for a -dimensional Hilbert space one would have to store values, the components of the wave function) and compresses it into one single number that then only contains some information about the localization properties of the state. Even though these two ...

  9. Phase space - Wikipedia

    en.wikipedia.org/wiki/Phase_space

    In a phase space, every degree of freedom or parameter of the system is represented as an axis of a multidimensional space; a one-dimensional system is called a phase line, while a two-dimensional system is called a phase plane. For every possible state of the system or allowed combination of values of the system's parameters, a point is ...