“List of equations in quantum mechanics”的意思、由来-开放百科全书

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List of equations in quantum mechanics

释义

Wavefunctions
Equations
Wave–particle duality and time evolution Non-relativistic time-independent Schrödinger equation Non-relativistic time-dependent Schrödinger equation Photoemission Quantum uncertainty Angular momentum The Hydrogen atom
See also
Footnotes
Sources
Further reading

This article summarizes equations in the theory of quantum mechanics.

Wavefunctions

A fundamental physical constant occurring in quantum mechanics is the Planck constant, h. A common abbreviation is {{nowrap|ħ {{=}} h/2π}}, also known as the reduced Planck constant or Dirac constant.

Wavefunction	ψ, Ψ	To solve from the Schrödinger equation	varies with situation and number of particles
Wavefunction probability density	ρ		m⁻³	[L]⁻³
Wavefunction probability current	j	Non-relativistic, no external field: star * is complex conjugate	m⁻² s⁻¹	[T]⁻¹ [L]⁻²

The general form of wavefunction for a system of particles, each with position r_i and z-component of spin s_{z i}. Sums are over the discrete variable s_z, integrals over continuous positions r.

For clarity and brevity, the coordinates are collected into tuples, the indices label the particles (which cannot be done physically, but is mathematically necessary). Following are general mathematical results, used in calculations.

Property or effect	Nomenclature	Equation
Wavefunction for N particles in 3d	r = (r₁, r₂... r_N) s_z = (s_{z 1}, s_{z 2}, ..., s_{z N})	In function notation: in bra–ket notation: for non-interacting particles:
Position-momentum Fourier transform (1 particle in 3d)	Φ = momentum-space wavefunction Ψ = position-space wavefunction
General probability distribution	V_j = volume (3d region) particle may occupy, P = Probability that particle 1 has position r₁ in volume V₁ with spin s_z1 and particle 2 has position r₂ in volume V₂ with spin s_z2, etc.
General normalization condition

Equations

Wave–particle duality and time evolution

Property or effect	Nomenclature	Equation
Planck–Einstein equation and de Broglie wavelength relations	P = (E/c, p) is the four-momentum, K = (ω/c, k) is the four-wavevector, E = energy of particle ω = 2πf is the angular frequency and frequency of the particle ħ = h/2π are the Planck constants c = speed of light
Schrödinger equation	Ψ = wavefunction of the system Ĥ = Hamiltonian operator, E = energy eigenvalue of system i is the imaginary unit t = time	General time-dependent case: Time-independent case:
Heisenberg equation	Â = operator of an observable property is the commutator denotes the average
Time evolution in Heisenberg picture (Ehrenfest theorem)	m = mass, V = potential energy, r = position, p = momentum, of a particle.	For momentum and position;

Non-relativistic time-independent Schrödinger equation

Summarized below are the various forms the Hamiltonian takes, with the corresponding Schrödinger equations and forms of wavefunction solutions. Notice in the case of one spatial dimension, for one particle, the partial derivative reduces to an ordinary derivative.

	One particle	N particles
One dimension		where the position of particle n is x_n.

	There is a further restriction — the solution must not grow at infinity, so that it has either a finite L²-norm (if it is a bound state) or a slowly diverging norm (if it is part of a continuum):^[1]	for non-interacting particles
Three dimensions	where the position of the particle is r = (x, y, z).	where the position of particle n is r _n = (x_n, y_n, z_n), and the Laplacian for particle n using the corresponding position coordinates is

		for non-interacting particles

Non-relativistic time-dependent Schrödinger equation

Again, summarized below are the various forms the Hamiltonian takes, with the corresponding Schrödinger equations and forms of solutions.

	One particle	N particles
One dimension		where the position of particle n is x_n.


Three dimensions
		This last equation is in a very high dimension,^[2] so the solutions are not easy to visualize.

Photoemission

Property/Effect	Nomenclature	Equation
Photoelectric equation	K_max = Maximum kinetic energy of ejected electron (J) h = Planck's constant f = frequency of incident photons (Hz = s⁻¹) φ, Φ = Work function of the material the photons are incident on (J)
Threshold frequency and	φ, Φ = Work function of the material the photons are incident on (J) f₀, ν₀ = Threshold frequency (Hz = s⁻¹)	Can only be found by experiment. The De Broglie relations give the relation between them:
Photon momentum	p = momentum of photon (kg m s⁻¹) f = frequency of photon (Hz = s⁻¹) λ = wavelength of photon (m) The De Broglie relations give:

Quantum uncertainty

Property or effect	Nomenclature	Equation
Heisenberg's uncertainty principles	n = number of photons φ = wave phase [, ] = commutator	Position-momentum Energy-time Number-phase
Dispersion of observable	A = observables (eigenvalues of operator)
General uncertainty relation	A, B = observables (eigenvalues of operator)

Probability Distributions
Property or effect	Nomenclature	Equation
Density of states
Fermi–Dirac distribution (fermions)	P(E_i) = probability of energy E_i g(E_i) = degeneracy of energy E_i (no of states with same energy) μ = chemical potential
Bose–Einstein distribution (bosons)

Angular momentum

Property or effect	Nomenclature	Equation
Angular momentum quantum numbers	s = spin quantum number m_s = spin magnetic quantum number ℓ = Azimuthal quantum number m_ℓ = azimuthal magnetic quantum number m_j = total angular momentum magnetic quantum number j = total angular momentum quantum number	Spin projection: Orbital: Total:
Angular momentum magnitudes	angular momementa: S = Spin, L = orbital, J = total	Spin magnitude: Orbital magnitude: Total magnitude:
Angular momentum components	Spin: Orbital:

Magnetic moments

In what follows, B is an applied external magnetic field and the quantum numbers above are used.

Property or effect	Nomenclature	Equation
orbital magnetic dipole moment	e = electron charge m_e = electron rest mass L = electron orbital angular momentum g_{{ell}} = orbital Landé g-factor μ_B = Bohr magneton	z-component:
spin magnetic dipole moment	S = electron spin angular momentum g_s = spin Landé g-factor	z-component:
dipole moment potential	U = potential energy of dipole in field

The Hydrogen atom

Property or effect	Nomenclature	Equation
Energy level :p≈	E_n = energy eigenvalue n = principal quantum number e = electron charge m_e = electron rest mass ε₀ = permittivity of free space h = Planck's constant
Spectrum	λ = wavelength of emitted photon, during electronic transition from E_i to E_j

Footnotes

1. ^{{cite book |last=Feynman |first=R.P. |last2=Leighton |first2=R.B. |last3=Sand |first3=M. |year=1964 |chapter=Operators |title=The Feynman Lectures on Physics |volume=3 |pages=20–7 |publisher=Addison-Wesley |isbn=0-201-02115-3}}
2. ^{{cite book |last=Shankar |first=R. |year=1994 |title=Principles of Quantum Mechanics |page=141 |publisher=Kluwer Academic/Plenum Publishers |isbn=978-0-306-44790-7}}

Sources

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