List of quantum mechanical systems with analytical solutions
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Much insight in
quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistr ...
can be gained from understanding the
closed-form solution In mathematics, a closed-form expression is a mathematical expression that uses a finite number of standard operations. It may contain constants, variables, certain well-known operations (e.g., + − × ÷), and functions (e.g., ''n''th roo ...
s to the time-dependent non-relativistic
Schrödinger equation The Schrödinger equation is a linear partial differential equation that governs the wave function of a quantum-mechanical system. It is a key result in quantum mechanics, and its discovery was a significant landmark in the development of th ...
. It takes the form : \hat \psi\left(\mathbf, t\right) = \left - \frac \nabla^2 + V\left(\mathbf\right) \right\psi\left(\mathbf, t\right) = i\hbar \frac, where \psi is the
wave function A wave function in quantum physics is a mathematical description of the quantum state of an isolated quantum system. The wave function is a complex-valued probability amplitude, and the probabilities for the possible results of measurements ...
of the system, \hat is the
Hamiltonian operator Hamiltonian may refer to: * Hamiltonian mechanics, a function that represents the total energy of a system * Hamiltonian (quantum mechanics), an operator corresponding to the total energy of that system ** Dyall Hamiltonian, a modified Hamiltonia ...
, and t is time.
Stationary state A stationary state is a quantum state with all observables independent of time. It is an eigenvector of the energy operator (instead of a quantum superposition of different energies). It is also called energy eigenvector, energy eigenstate, ener ...
s of this equation are found by solving the time-independent Schrödinger equation, : \left - \frac \nabla^2 + V\left(\mathbf\right) \right\psi\left(\mathbf\right) = E \psi \left(\mathbf\right), which is an eigenvalue equation. Very often, only numerical solutions to the Schrödinger equation can be found for a given physical system and its associated potential energy. However, there exists a subset of physical systems for which the form of the eigenfunctions and their associated energies, or eigenvalues, can be found. These quantum-mechanical systems with analytical solutions are listed below.


Solvable systems

*The
two-state quantum system In quantum mechanics, a two-state system (also known as a two-level system) is a quantum system that can exist in any quantum superposition of two independent (physically distinguishable) quantum states. The Hilbert space describing such a sys ...
(the simplest possible quantum system) *The
free particle In physics, a free particle is a particle that, in some sense, is not bound by an external force, or equivalently not in a region where its potential energy varies. In classical physics, this means the particle is present in a "field-free" space. I ...
*The
delta potential In quantum mechanics the delta potential is a potential well mathematically described by the Dirac delta function - a generalized function. Qualitatively, it corresponds to a potential which is zero everywhere, except at a single point, where it t ...
*The double-well Dirac delta potential *The
particle in a box In quantum mechanics, the particle in a box model (also known as the infinite potential well or the infinite square well) describes a particle free to move in a small space surrounded by impenetrable barriers. The model is mainly used as a hypo ...
/
infinite potential well In quantum mechanics, the particle in a box model (also known as the infinite potential well or the infinite square well) describes a particle free to move in a small space surrounded by impenetrable barriers. The model is mainly used as a hypo ...
*The
finite potential well The finite potential well (also known as the finite square well) is a concept from quantum mechanics. It is an extension of the infinite potential well, in which a particle is confined to a "box", but one which has finite potential "walls". Unlike ...
*The one-dimensional triangular potential *The
particle in a ring In quantum mechanics, the case of a particle in a one-dimensional ring is similar to the particle in a box. The Schrödinger equation for a free particle which is restricted to a ring (technically, whose configuration space is the circle S^1) is : ...
or
ring wave guide In quantum mechanics, the case of a particle in a one-dimensional ring is similar to the particle in a box. The Schrödinger equation for a free particle which is restricted to a ring (technically, whose configuration space is the circle S^1) is : ...
*The
particle in a spherically symmetric potential In the quantum mechanics description of a particle in spherical coordinates, a spherically symmetric potential, is a potential that depends only on the distance between the particle and a defined centre point. One example of a spherical potential ...
*The quantum harmonic oscillator *The quantum harmonic oscillator with an applied uniform field *The hydrogen atom or
hydrogen-like atom A hydrogen-like atom (or hydrogenic atom) is any atom or ion with a single valence electron. These atoms are isoelectronic with hydrogen. Examples of hydrogen-like atoms include, but are not limited to, hydrogen itself, all alkali metals such a ...
e.g.
positronium Positronium (Ps) is a system consisting of an electron and its anti-particle, a positron, bound together into an exotic atom, specifically an onium. Unlike hydrogen, the system has no protons. The system is unstable: the two particles annih ...
*The hydrogen atom in a spherical cavity with
Dirichlet boundary condition In the mathematical study of differential equations, the Dirichlet (or first-type) boundary condition is a type of boundary condition, named after Peter Gustav Lejeune Dirichlet (1805–1859). When imposed on an ordinary or a partial differential ...
s *The
particle in a one-dimensional lattice (periodic potential) In quantum mechanics, the particle in a one-dimensional lattice is a problem that occurs in the model of a periodic crystal lattice. The potential is caused by ions in the periodic structure of the crystal creating an electromagnetic field so el ...
*The
particle in a one-dimensional lattice of finite length ''L = N a'' (''N'' is a positive integer, ''a'' is the potential period) In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from ...
*The Morse potential * The Mie potential *The step potential *The Rigid rotor#Quantum mechanical linear rigid rotor, linear rigid rotor *The Rigid rotor#Quantum mechanical rigid rotor, symmetric top *The Hooke's atom *The Spherium atom *Zero range interaction in a harmonic trap *The quantum pendulum *The rectangular potential barrier *The Pöschl–Teller potential *The Inverse square root potential * Multistate Landau–Zener models *The Luttinger liquid (the only exact quantum mechanical solution to a model including interparticle interactions)


See also

* List of quantum-mechanical potentials – a list of physically relevant potentials without regard to analytic solubility * List of integrable models * WKB approximation * Quasi-exactly-solvable problems


References


Reading materials

* {{cite book , last = Mattis , first = Daniel C. , authorlink = Daniel C. Mattis , title = The Many-Body Problem: An Encyclopedia of Exactly Solved Models in One Dimension , publisher = World Scientific , date = 1993 , isbn = 978-981-02-0975-9 Quantum models Physics-related lists, Quantum-mechanical systems with analytical solutions