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This page provides a list of the most important formulas in quantum mechanics, useful as a quick reference for students, teachers, and researchers. The formulas are organized by topic and include names, mathematical expressions, and short explanations of what they mean and how they are used. While this collection focuses on key results, science is always evolving, and new discoveries may override or extend these formulas. You, the reader, are welcome to suggest additions or corrections to keep this resource up to date.
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'''Formulas Collection''' this page provides a list of the most important formulas in quantum mechanics, useful as a quick reference for students, teachers, and researchers. The formulas are organized by topic and include names, mathematical expressions, and short explanations of what they mean and how they are used. While this collection focuses on key results, science is always evolving, and new discoveries may override or extend these formulas. You, the reader, are welcome to suggest additions or corrections to keep this resource up to date. This page provides a list of the most important formulas in quantum mechanics, useful as a quick reference for students, teachers, and researchers. This table lists key formulas in quantum mechanics, showing their names, expressions, and applications.
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[[File:Collection of quantum formulas.jpg|thumb|280px|Quantum Formulas Collection.]]
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[[File:Collection of quantum formulas.jpg|thumb|450px]]
=== Key Formulas in Quantum Mechanics ===
=== Key Formulas in Quantum Mechanics ===


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! Applications
! Applications
|-
|-
| [[Wikipedia:Angular momentum operator|Angular Momentum Components]]
| Angular Momentum Components
| <math>L_z = m_{\ell} \hbar</math>
| <math>L_z = m_{\ell} \hbar</math>
| Z-component of angular momentum.
| Z-component of angular momentum.
| Quantized orbits.
| Quantized orbits.
|-
|-
| [[Wikipedia:Compton scattering|Compton Effect: Change in Wavelength]]
| Compton Effect: Change in Wavelength
| <math>\Delta \lambda = \frac{h}{m_e c} (1 - \cos \theta)</math>
| <math>\Delta \lambda = \frac{h}{m_e c} (1 - \cos \theta)</math>
| Shift in photon wavelength after scattering.
| Shift in photon wavelength after scattering.
| Compton scattering, evidence for photon momentum.
| Compton scattering, evidence for photon momentum.
|-
|-
| [[Wikipedia:Duane–Hunt law|Cutoff Wavelength]]
| Cutoff Wavelength
| <math>\lambda_{min} = \frac{h c}{K_0}</math>
| <math>\lambda_{min} = \frac{h c}{K_0}</math>
| Minimum wavelength in bremsstrahlung.
| Minimum wavelength in bremsstrahlung.
| X-ray production.
| X-ray production.
|-
|-
| [[Wikipedia:Matter wave|De Broglie Wavelength]]
| De Broglie Wavelength
| <math>p = \frac{h}{\lambda} = \hbar k</math>
| <math>p = \frac{h}{\lambda} = \hbar k</math>
| Wavelength associated with a particle's momentum.
| Wavelength associated with a particle's momentum.
| Matter waves, electron diffraction.
| Matter waves, electron diffraction.
|-
|-
| [[Wikipedia:Fermi–Dirac statistics|Occupancy Probability]]
| Occupancy Probability
| <math>P(E) = \frac{1}{e^{(E - E_F)/kT} + 1}</math>
| <math>P(E) = \frac{1}{e^{(E - E_F)/kT} + 1}</math>
| Fermi-Dirac distribution.
| Fermi-Dirac distribution.
| Electron statistics in metals.
| Electron statistics in metals.
|-
|-
| [[Wikipedia:Free electron model|Density of States]]
| Density of States
| <math>N(E) = 8 \sqrt{2} \pi m^{3/2} E^{1/2} / h^3</math>
| <math>N(E) = 8 \sqrt{2} \pi m^{3/2} E^{1/2} / h^3</math>
| Number of states per energy interval (3D free electron gas).
| Number of states per energy interval (3D free electron gas).
| Solid-state physics, Fermi gas.
| Solid-state physics, Fermi gas.
|-
|-
| [[Wikipedia:Dirac equation|Dirac Equation]]
| Dirac Equation
| <math>\left( \boldsymbol{\beta} m c^2 + c \sum_{k=1}^{3} \boldsymbol{\alpha}_k p_k \right) \Psi = i \hbar \frac{\partial}{\partial t} \Psi</math>
| <math>\left( \boldsymbol{\beta} m c^2 + c \sum_{k=1}^{3} \boldsymbol{\alpha}_k p_k \right) \Psi = i \hbar \frac{\partial}{\partial t} \Psi</math>
| Relativistic quantum equation for fermions.
| Relativistic quantum equation for fermions.
| Particle physics, electrons.
| Particle physics, electrons.
|-
|-
| [[Wikipedia:Electric dipole moment|Electric Dipole Potential Energy]]
| Electric Dipole Potential Energy
| <math>V = -\mathbf{p} \cdot \mathbf{E}</math>
| <math>V = -\mathbf{p} \cdot \mathbf{E}</math>
| Energy of dipole in electric field.
| Energy of dipole in electric field.
| Molecular physics.
| Molecular physics.
|-
|-
| [[Wikipedia:Coulomb potential|Electrostatic, Coulomb Potential Energy]]
| Electrostatic, Coulomb Potential Energy
| <math>V = \frac{q_1 q_2}{4 \pi \epsilon_0 r}</math>
| <math>V = \frac{q_1 q_2}{4 \pi \epsilon_0 r}</math>
| Coulomb potential.
| Coulomb potential.
| Atomic interactions.
| Atomic interactions.
|-
|-
| [[Wikipedia:Free particle|Free Particle Schrödinger's Equation (1D)]]
| Free Particle Schrödinger's Equation (1D)
| <math>-\frac{\hbar^2}{2m} \frac{\mathrm{d}^2}{\mathrm{d} x^2} \Psi = E \Psi</math>
| <math>-\frac{\hbar^2}{2m} \frac{\mathrm{d}^2}{\mathrm{d} x^2} \Psi = E \Psi</math>
| For free particle in 1D.
| For free particle in 1D.
| Free particle motion.
| Free particle motion.
|-
|-
| [[Wikipedia:Free particle|Free Particle Schrödinger's Equation (3D)]]
| Free Particle Schrödinger's Equation (3D)
| <math>-\frac{\hbar^2}{2m} \nabla^2 \Psi = E \Psi</math>
| <math>-\frac{\hbar^2}{2m} \nabla^2 \Psi = E \Psi</math>
| For free particle in 3D.
| For free particle in 3D.
| Scattering problems.
| Scattering problems.
|-
|-
| [[Wikipedia:Quantum harmonic oscillator|Harmonic Oscillator Potential Energy]]
| Harmonic Oscillator Potential Energy
| <math>V = \frac{1}{2} k x^2</math>
| <math>V = \frac{1}{2} k x^2</math>
| Potential for harmonic oscillator.
| Potential for harmonic oscillator.
| Vibrational modes, quantum optics.
| Vibrational modes, quantum optics.
|-
|-
| [[Wikipedia:Uncertainty principle|Heisenberg's Uncertainty Principle]]
| Heisenberg's Uncertainty Principle
| <math>\Delta x \Delta p_x \geq \frac{\hbar}{2}</math> <br /> <math>\Delta E \Delta t \geq \frac{\hbar}{2}</math>
| <math>\Delta x \Delta p_x \geq \frac{\hbar}{2}</math> <br /> <math>\Delta E \Delta t \geq \frac{\hbar}{2}</math>
| Limits on simultaneous knowledge of position/momentum and energy/time.
| Limits on simultaneous knowledge of position/momentum and energy/time.
| Fundamental limit in measurements, quantum tunneling.
| Fundamental limit in measurements, quantum tunneling.
|-
|-
| [[Wikipedia:Hydrogen atom|Hydrogen Atom, Orbital Energy]]
| Hydrogen Atom, Orbital Energy
| <math>E_n = -\frac{m e^4}{8 \epsilon_0^2 h^2 n^2} = -\frac{13.6 \, \mathrm{eV}}{n^2}</math>
| <math>E_n = -\frac{m e^4}{8 \epsilon_0^2 h^2 n^2} = -\frac{13.6 \, \mathrm{eV}}{n^2}</math>
| Energy levels of hydrogen atom.
| Energy levels of hydrogen atom.
| Atomic spectroscopy, Bohr model.
| Atomic spectroscopy, Bohr model.
|-
|-
| [[Wikipedia:Radial distribution function|Hydrogen Atom, Radial Probability Density]]
| Hydrogen Atom, Radial Probability Density
| <math>P(r) = \frac{4 r^2}{a^3} e^{-2r/a}</math>
| <math>P(r) = \frac{4 r^2}{a^3} e^{-2r/a}</math>
| Probability density for electron position (ground state).
| Probability density for electron position (ground state).
| Atomic orbitals.
| Atomic orbitals.
|-
|-
| [[Wikipedia:Hydrogen spectral series|Hydrogen Atom Spectrum, Rydberg Equation]]
| Hydrogen Atom Spectrum, Rydberg Equation
| <math>\frac{1}{\lambda} = R_H \left( \frac{1}{n_2^2} - \frac{1}{n_1^2} \right)</math>
| <math>\frac{1}{\lambda} = R_H \left( \frac{1}{n_2^2} - \frac{1}{n_1^2} \right)</math>
| Wavelengths of spectral lines.
| Wavelengths of spectral lines.
| Hydrogen emission/absorption spectra.
| Hydrogen emission/absorption spectra.
|-
|-
| [[Wikipedia:Particle in a box|Infinite Potential Well Energy Levels]]
| Infinite Potential Well Energy Levels
| <math>E_n = \left( \frac{h n}{2L} \right)^2 \frac{1}{2m}</math>
| <math>E_n = \left( \frac{h n}{2L} \right)^2 \frac{1}{2m}</math>
| Energy levels for particle in a box.
| Energy levels for particle in a box.
| Quantum confinement, nanostructures.
| Quantum confinement, nanostructures.
|-
|-
| [[Wikipedia:Klein–Gordon equation|Klein-Gordon Equation]]
| Klein-Gordon Equation
| <math>\left( -\frac{1}{c^2} \frac{\partial^2}{\partial t^2} + \nabla^2 \right) \Psi = \left( \frac{m_0 c}{\hbar} \right)^2 \Psi</math>
| <math>\left( -\frac{1}{c^2} \frac{\partial^2}{\partial t^2} + \nabla^2 \right) \Psi = \left( \frac{m_0 c}{\hbar} \right)^2 \Psi</math>
| Relativistic equation for bosons.
| Relativistic equation for bosons.
| Scalar particles.
| Scalar particles.
|-
|-
| [[Wikipedia:Probability current|Law of Probability Conservation for Quantum Mechanics]]
| Law of Probability Conservation for Quantum Mechanics
| <math>\frac{\partial}{\partial t} \int_V |\Psi|^2 \, \mathrm{d} V + \int_S \mathbf{j} \cdot \mathrm{d} \mathbf{A} = 0</math>
| <math>\frac{\partial}{\partial t} \int_V |\Psi|^2 \, \mathrm{d} V + \int_S \mathbf{j} \cdot \mathrm{d} \mathbf{A} = 0</math>
| Conservation of probability.
| Conservation of probability.
| Quantum dynamics.
| Quantum dynamics.
|-
|-
| [[Wikipedia:Magnetic moment|Magnetic Dipole Potential Energy]]
| Magnetic Dipole Potential Energy
| <math>V = -\mathbf{m} \cdot \mathbf{B}</math>
| <math>V = -\mathbf{m} \cdot \mathbf{B}</math>
| Energy of dipole in magnetic field.
| Energy of dipole in magnetic field.
| Magnetic resonance.
| Magnetic resonance.
|-
|-
| [[Wikipedia:Moseley's law|Moseley's Law]]
| Moseley's Law
| <math>f = \frac{c}{\lambda} = M_{K_{\alpha}} (Z-1)^2</math> <br /> <math>M_{K_{\alpha}} = 2.47 \times 10^{15}</math> Hz
| <math>f = \frac{c}{\lambda} = M_{K_{\alpha}} (Z-1)^2</math> <br /> <math>M_{K_{\alpha}} = 2.47 \times 10^{15}</math> Hz
| Frequency of K-α X-ray line.
| Frequency of K-α X-ray line.
| Atomic number determination, X-ray spectroscopy.
| Atomic number determination, X-ray spectroscopy.
|-
|-
| [[Wikipedia:Born rule|Normalization Integral]]
| Normalization Integral
| <math>\int_{\mathbf{r} \in R} |\Psi|^2 \, \mathrm{d} V = 1</math>
| <math>\int_{\mathbf{r} \in R} |\Psi|^2 \, \mathrm{d} V = 1</math>
| Normalizes the wavefunction.
| Normalizes the wavefunction.
| Probability calculations.
| Probability calculations.
|-
|-
| [[Wikipedia:Particle in a box|One-Dimensional Box Potential Energy]]
| One-Dimensional Box Potential Energy
| <math>V = \begin{cases} 0 & x \in [a, b] \\ \infty & x \notin [a, b] \end{cases}</math>
| <math>V = \begin{cases} 0 & x \in [a, b] \\ \infty & x \notin [a, b] \end{cases}</math>
| Potential for particle in a box.
| Potential for particle in a box.
| Quantum wells.
| Quantum wells.
|-
|-
| [[Wikipedia:Zeeman effect|Orbital Electron Magnetic Dipole Components]]
| Orbital Electron Magnetic Dipole Components
| <math>\mathbf{\mu}_{orb, z} = -m_{\ell} \mu_B</math>
| <math>\mathbf{\mu}_{orb, z} = -m_{\ell} \mu_B</math>
| Z-component of orbital magnetic moment.
| Z-component of orbital magnetic moment.
| Zeeman effect.
| Zeeman effect.
|-
|-
| [[Wikipedia:Electron magnetic moment|Orbital Electron Magnetic Dipole Moment]]
| Orbital Electron Magnetic Dipole Moment
| <math>\mathbf{\mu}_{orb} = -e \mathbf{L} / 2m</math>
| <math>\mathbf{\mu}_{orb} = -e \mathbf{L} / 2m</math>
| Magnetic moment due to orbital motion.
| Magnetic moment due to orbital motion.
| Atomic magnetism.
| Atomic magnetism.
|-
|-
| [[Wikipedia:Zeeman effect|Orbital, Electron Magnetic Dipole Moment Potential]]
| Orbital, Electron Magnetic Dipole Moment Potential
| <math>U = -\mathbf{\mu}_{orb} \cdot \mathbf{B}_{ext} = -\mu_{orb, z} B_{ext}</math>
| <math>U = -\mathbf{\mu}_{orb} \cdot \mathbf{B}_{ext} = -\mu_{orb, z} B_{ext}</math>
| Potential in external field.
| Potential in external field.
| Magnetic interactions.
| Magnetic interactions.
|-
|-
| [[Wikipedia:Electron magnetic moment|Spin, Electron Magnetic Dipole Moment]]
| Spin, Electron Magnetic Dipole Moment
| <math>\mathbf{\mu_s} = - \frac{e}{m}\mathbf{S} = - g \frac{e}{2m} \mathbf{S}</math>
| <math>\mathbf{\mu_s} = - \frac{e}{m}\mathbf{S} = - g \frac{e}{2m} \mathbf{S}</math>
| Spin magnetic moment.
| Spin magnetic moment.
| Electron spin resonance.
| Electron spin resonance.
|-
|-
| [[Wikipedia:Photoelectric effect|Photoelectric Effect: Maximum Kinetic Energy]]
| Photoelectric Effect: Maximum Kinetic Energy
| <math>E_{\mathrm{k\;\!max}} = hf - \Phi</math>
| <math>E_{\mathrm{k\;\!max}} = hf - \Phi</math>
| Maximum kinetic energy of photoelectrons.
| Maximum kinetic energy of photoelectrons.
| Photoelectric effect experiments, solar cells.
| Photoelectric effect experiments, solar cells.
|-
|-
| [[Wikipedia:Photon#Physical_properties|Photon Momentum]]
| Photon Momentum
| <math>p = \frac{hf}{c} = \frac{h}{\lambda}</math>
| <math>p = \frac{hf}{c} = \frac{h}{\lambda}</math>
| Momentum of a photon.
| Momentum of a photon.
| Quantum optics, Compton scattering.
| Quantum optics, Compton scattering.
|-
|-
| [[Wikipedia:Planck relation|Planck–Einstein Equation]]
| Planck–Einstein Equation
| <math>E = hf = \frac{hc}{\lambda}</math>
| <math>E = hf = \frac{hc}{\lambda}</math>
| Relates energy of a photon to its frequency or wavelength.
| Relates energy of a photon to its frequency or wavelength.
| Wave-particle duality, photon energy calculations.
| Wave-particle duality, photon energy calculations.
|-
|-
| [[Wikipedia:Planck's law|Planck's Radiation Law (Frequency Form)]]
| Planck's Radiation Law (Frequency Form)
| <math>I(\nu, T) = \frac{2h\nu^3}{c^2} \frac{1}{e^{\frac{h\nu}{kT}} - 1}</math>
| <math>I(\nu, T) = \frac{2h\nu^3}{c^2} \frac{1}{e^{\frac{h\nu}{kT}} - 1}</math>
| Spectral radiance for blackbody in frequency.
| Spectral radiance for blackbody in frequency.
| Blackbody radiation, stellar spectra.
| Blackbody radiation, stellar spectra.
|-
|-
| [[Wikipedia:Planck's law|Planck's Radiation Law (Wavelength Form)]]
| Planck's Radiation Law (Wavelength Form)
| <math>I(\lambda, T) = \frac{2hc^2}{\lambda^5} \frac{1}{e^{\frac{hc}{\lambda kT}} - 1}</math>
| <math>I(\lambda, T) = \frac{2hc^2}{\lambda^5} \frac{1}{e^{\frac{hc}{\lambda kT}} - 1}</math>
| Spectral radiance for blackbody in wavelength.
| Spectral radiance for blackbody in wavelength.
| Thermal radiation analysis.
| Thermal radiation analysis.
|-
|-
| [[Wikipedia:Probability current|Probability Current (Non-Relativistic)]]
| Probability Current (Non-Relativistic)
| <math>\mathbf{j} = \frac{\hbar}{2 m i} (\Psi^* \nabla \Psi - \Psi \nabla \Psi^*)</math>
| <math>\mathbf{j} = \frac{\hbar}{2 m i} (\Psi^* \nabla \Psi - \Psi \nabla \Psi^*)</math>
| Flow of probability.
| Flow of probability.
| Current in quantum systems.
| Current in quantum systems.
|-
|-
| [[Wikipedia:Probability density function|Probability Density Function]]
| Probability Density Function
| <math>\rho(\mathbf{r}, t) = |\Psi(\mathbf{r}, t)|^2</math>
| <math>\rho(\mathbf{r}, t) = |\Psi(\mathbf{r}, t)|^2</math>
| Probability density.
| Probability density.
| Locating particles.
| Locating particles.
|-
|-
| [[Wikipedia:Schrödinger equation|Schrödinger's Equation (General Form)]]
| Schrödinger's Equation (General Form)
| <math>\hat{H} \Psi = E \Psi</math>
| <math>\hat{H} \Psi = E \Psi</math>
| Fundamental equation of quantum mechanics.
| Fundamental equation of quantum mechanics.
| Solving quantum systems.
| Solving quantum systems.
|-
|-
| [[Wikipedia:Spin (physics)|Spin Angular Momentum Magnitude]]
| Spin Angular Momentum Magnitude
| <math>S = \hbar \sqrt{s(s+1)}</math>
| <math>S = \hbar \sqrt{s(s+1)}</math>
| Magnitude of spin.
| Magnitude of spin.
| Particle spin properties.
| Particle spin properties.
|-
|-
| [[Wikipedia:Spin (physics)|Spin Projection Quantum Number]]
| Spin Projection Quantum Number
| <math>m_s \in \left\{ -\frac{1}{2}, +\frac{1}{2} \right\}</math>
| <math>m_s \in \left\{ -\frac{1}{2}, +\frac{1}{2} \right\}</math>
| Spin along z-axis for electrons.
| Spin along z-axis for electrons.
| Spintronics, NMR.
| Spintronics, NMR.
|-
|-
| [[Wikipedia:Schrödinger equation|Time-Dependent Schrödinger's Equation (1D)]]
| Time-Dependent Schrödinger's Equation (1D)
| <math>\left( -\frac{\hbar^2}{2m} \frac{\partial^2}{\partial x^2} + V \right) \Psi = i \hbar \frac{\partial}{\partial t} \Psi</math>
| <math>\left( -\frac{\hbar^2}{2m} \frac{\partial^2}{\partial x^2} + V \right) \Psi = i \hbar \frac{\partial}{\partial t} \Psi</math>
| Time evolution in 1D.
| Time evolution in 1D.
| Dynamics of quantum systems.
| Dynamics of quantum systems.
|-
|-
| [[Wikipedia:Schrödinger equation|Time-Dependent Schrödinger's Equation (3D)]]
| Time-Dependent Schrödinger's Equation (3D)
| <math>\left( -\frac{\hbar^2}{2m} \nabla^2 + V \right) \Psi = i \hbar \frac{\partial}{\partial t} \Psi</math>
| <math>\left( -\frac{\hbar^2}{2m} \nabla^2 + V \right) \Psi = i \hbar \frac{\partial}{\partial t} \Psi</math>
| Time evolution in 3D.
| Time evolution in 3D.
| Quantum simulations.
| Quantum simulations.
|-
|-
| [[Wikipedia:Schrödinger equation|Time-Independent Schrödinger's Equation (1D)]]
| Time-Independent Schrödinger's Equation (1D)
| <math>\left( -\frac{\hbar^2}{2m} \frac{\mathrm{d}^2}{\mathrm{d} x^2} + V \right) \Psi = E \Psi</math>
| <math>\left( -\frac{\hbar^2}{2m} \frac{\mathrm{d}^2}{\mathrm{d} x^2} + V \right) \Psi = E \Psi</math>
| Stationary states in 1D.
| Stationary states in 1D.
| Bound states, potentials.
| Bound states, potentials.
|-
|-
| [[Wikipedia:Schrödinger equation|Time-Independent Schrödinger's Equation (3D)]]
| Time-Independent Schrödinger's Equation (3D)
| <math>\left( -\frac{\hbar^2}{2m} \nabla^2 + V \right) \Psi = E \Psi</math>
| <math>\left( -\frac{\hbar^2}{2m} \nabla^2 + V \right) \Psi = E \Psi</math>
| Stationary states in 3D.
| Stationary states in 3D.
| Atomic and molecular physics.
| Atomic and molecular physics.
|-
|-
| [[Wikipedia:Particle in a box|Wavefunction of a Trapped Particle, One Dimensional Box]]
| Wavefunction of a Trapped Particle, One Dimensional Box
| <math>\Psi_n(x) = A \sin \left( \frac{n \pi x}{L} \right)</math>
| <math>\Psi_n(x) = A \sin \left( \frac{n \pi x}{L} \right)</math>
| Wavefunction for particle in a box.
| Wavefunction for particle in a box.
| Bound states, quantum wells.
| Bound states, quantum wells.
|-
|-
| [[Wikipedia:Work function|Work Function]]
| Work Function
| <math>\Phi = hf_0</math>
| <math>\Phi = hf_0</math>
| Minimum energy to eject an electron.
| Minimum energy to eject an electron.
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=See also=
=See also=
{{#invoke:PhysicsQC|tocHeadingAndList|Physics:Quantum basics/See also}}
{{#invoke:PhysicsQC|tocHeadingAndList|Physics:Quantum basics/See also}}
== References ==
{{reflist|3}}
{{Author|Harold Foppele}}
{{Author|Harold Foppele}}
[[Category:Quantum mechanics]]
[[Category:Quantum mechanics]]


{{Sourceattribution|Quantum Formulas Collection|1}}
{{Sourceattribution|Physics:Quantum Formulas Collection|1}}

Latest revision as of 21:58, 20 May 2026



← Previous : Many-body problem
Next : A Matter Of Size →

Formulas Collection this page provides a list of the most important formulas in quantum mechanics, useful as a quick reference for students, teachers, and researchers. The formulas are organized by topic and include names, mathematical expressions, and short explanations of what they mean and how they are used. While this collection focuses on key results, science is always evolving, and new discoveries may override or extend these formulas. You, the reader, are welcome to suggest additions or corrections to keep this resource up to date. This page provides a list of the most important formulas in quantum mechanics, useful as a quick reference for students, teachers, and researchers. This table lists key formulas in quantum mechanics, showing their names, expressions, and applications.

Quantum Formulas Collection.

Key Formulas in Quantum Mechanics

This table lists key formulas in quantum mechanics, showing their names, expressions, and applications.

Equation Name Formula Description Applications
Angular Momentum Components Lz=m Z-component of angular momentum. Quantized orbits.
Compton Effect: Change in Wavelength Δλ=hmec(1cosθ) Shift in photon wavelength after scattering. Compton scattering, evidence for photon momentum.
Cutoff Wavelength λmin=hcK0 Minimum wavelength in bremsstrahlung. X-ray production.
De Broglie Wavelength p=hλ=k Wavelength associated with a particle's momentum. Matter waves, electron diffraction.
Occupancy Probability P(E)=1e(EEF)/kT+1 Fermi-Dirac distribution. Electron statistics in metals.
Density of States N(E)=82πm3/2E1/2/h3 Number of states per energy interval (3D free electron gas). Solid-state physics, Fermi gas.
Dirac Equation (βmc2+ck=13αkpk)Ψ=itΨ Relativistic quantum equation for fermions. Particle physics, electrons.
Electric Dipole Potential Energy V=𝐩𝐄 Energy of dipole in electric field. Molecular physics.
Electrostatic, Coulomb Potential Energy V=q1q24πϵ0r Coulomb potential. Atomic interactions.
Free Particle Schrödinger's Equation (1D) 22md2dx2Ψ=EΨ For free particle in 1D. Free particle motion.
Free Particle Schrödinger's Equation (3D) 22m2Ψ=EΨ For free particle in 3D. Scattering problems.
Harmonic Oscillator Potential Energy V=12kx2 Potential for harmonic oscillator. Vibrational modes, quantum optics.
Heisenberg's Uncertainty Principle ΔxΔpx2
ΔEΔt2
Limits on simultaneous knowledge of position/momentum and energy/time. Fundamental limit in measurements, quantum tunneling.
Hydrogen Atom, Orbital Energy En=me48ϵ02h2n2=13.6eVn2 Energy levels of hydrogen atom. Atomic spectroscopy, Bohr model.
Hydrogen Atom, Radial Probability Density P(r)=4r2a3e2r/a Probability density for electron position (ground state). Atomic orbitals.
Hydrogen Atom Spectrum, Rydberg Equation 1λ=RH(1n221n12) Wavelengths of spectral lines. Hydrogen emission/absorption spectra.
Infinite Potential Well Energy Levels En=(hn2L)212m Energy levels for particle in a box. Quantum confinement, nanostructures.
Klein-Gordon Equation (1c22t2+2)Ψ=(m0c)2Ψ Relativistic equation for bosons. Scalar particles.
Law of Probability Conservation for Quantum Mechanics tV|Ψ|2dV+S𝐣d𝐀=0 Conservation of probability. Quantum dynamics.
Magnetic Dipole Potential Energy V=𝐦𝐁 Energy of dipole in magnetic field. Magnetic resonance.
Moseley's Law f=cλ=MKα(Z1)2
MKα=2.47×1015 Hz
Frequency of K-α X-ray line. Atomic number determination, X-ray spectroscopy.
Normalization Integral 𝐫R|Ψ|2dV=1 Normalizes the wavefunction. Probability calculations.
One-Dimensional Box Potential Energy V={0x[a,b]x[a,b] Potential for particle in a box. Quantum wells.
Orbital Electron Magnetic Dipole Components μorb,z=mμB Z-component of orbital magnetic moment. Zeeman effect.
Orbital Electron Magnetic Dipole Moment μorb=e𝐋/2m Magnetic moment due to orbital motion. Atomic magnetism.
Orbital, Electron Magnetic Dipole Moment Potential U=μorb𝐁ext=μorb,zBext Potential in external field. Magnetic interactions.
Spin, Electron Magnetic Dipole Moment μ𝐬=em𝐒=ge2m𝐒 Spin magnetic moment. Electron spin resonance.
Photoelectric Effect: Maximum Kinetic Energy Ekmax=hfΦ Maximum kinetic energy of photoelectrons. Photoelectric effect experiments, solar cells.
Photon Momentum p=hfc=hλ Momentum of a photon. Quantum optics, Compton scattering.
Planck–Einstein Equation E=hf=hcλ Relates energy of a photon to its frequency or wavelength. Wave-particle duality, photon energy calculations.
Planck's Radiation Law (Frequency Form) I(ν,T)=2hν3c21ehνkT1 Spectral radiance for blackbody in frequency. Blackbody radiation, stellar spectra.
Planck's Radiation Law (Wavelength Form) I(λ,T)=2hc2λ51ehcλkT1 Spectral radiance for blackbody in wavelength. Thermal radiation analysis.
Probability Current (Non-Relativistic) 𝐣=2mi(Ψ*ΨΨΨ*) Flow of probability. Current in quantum systems.
Probability Density Function ρ(𝐫,t)=|Ψ(𝐫,t)|2 Probability density. Locating particles.
Schrödinger's Equation (General Form) H^Ψ=EΨ Fundamental equation of quantum mechanics. Solving quantum systems.
Spin Angular Momentum Magnitude S=s(s+1) Magnitude of spin. Particle spin properties.
Spin Projection Quantum Number ms{12,+12} Spin along z-axis for electrons. Spintronics, NMR.
Time-Dependent Schrödinger's Equation (1D) (22m2x2+V)Ψ=itΨ Time evolution in 1D. Dynamics of quantum systems.
Time-Dependent Schrödinger's Equation (3D) (22m2+V)Ψ=itΨ Time evolution in 3D. Quantum simulations.
Time-Independent Schrödinger's Equation (1D) (22md2dx2+V)Ψ=EΨ Stationary states in 1D. Bound states, potentials.
Time-Independent Schrödinger's Equation (3D) (22m2+V)Ψ=EΨ Stationary states in 3D. Atomic and molecular physics.
Wavefunction of a Trapped Particle, One Dimensional Box Ψn(x)=Asin(nπxL) Wavefunction for particle in a box. Bound states, quantum wells.
Work Function Φ=hf0 Minimum energy to eject an electron. Photoelectric effect, surface physics.

2. Organized by topic

Below are the same formulas grouped

Quantum mechanics (QM)



Core Dynamical Equations

Time-Dependent Schrödinger Equation i,tΨ=H^Ψ

Time-Independent Schrödinger Equation H^ψ=Eψ

Time-Evolution Operator U(t)=eiH^t/

Operators and Measurement Theory

Canonical Commutation Relation (Heisenberg) [x,p]=i

Expectation Value A=ψ|A|ψ

Born Rule (Measurement Probability) P(a)=|a|ψ|2

Harmonic Oscillator

Annihilation Operator a=12mω,(mωx+ip)

Energy Levels En=ω(n+12)

Perturbation Theory & Quantum Transitions

First-Order Energy Correction En(1)=n|V|n

Fermi Golden Rule (Transition Rate) Γ=2π,|Vfi|2,ρ(E)

Continuity Equation & Probability Current

Probability Current j=2mi(ψψψψ)

Open quantum systems

  • Density Matrix (Statistical Mixture) ρ=ipi,|ψiψi|
  • Lindblad Master Equation (Markovian Open Systems) ρ˙=i[H^,ρ]+k𝒟[Lk]ρ
  • von Neumann Entropy S=Tr(ρlogρ)

Quantum information science (QIS)

I(A:B)=S(A)+S(B)S(AB)

Φ(ρ)=kAkρAk (quantum channels)

  • Bell states |ψ±, |ϕ±
  • CNOT gate definition
  • Qubit superposition |ψ=α|0+β|1

Quantum optics (QO)

a,a creation–annihilation operators

Hint=𝐝𝐄

  • Coherent state |α=e|α|2/2nαnn!|n
  • Jaynes–Cummings Hamiltonian H=ωaa+12ω0σz+g(aσ+aσ+)

Quantum statistical mechanics

  • Partition function Z=Tr(eβH)
  • Thermal state ρβ=eβH/Z
  • Response function χ(ω)

Quantum field theory (QFT)

  • Canonical commutation [ϕ(x),π(y)]=iδ(xy)
  • Klein–Gordon equation (+m2)ϕ=0
  • Dirac Lagrangian
  • Relativistic dispersion E2=p2c2+m2c4

3. Multi column version

  • itΨ=HΨ
  • Hψ=Eψ
  • ΔxΔp/2
  • [x,p]=i
  • P(a)=|a|ψ|2
  • ρ=pi|ψiψi|
  • S=Tr(ρlogρ)
  • En=ω(n+1/2)
  • a=(mωx+ip)/2mω
  • Γ=2π|Vfi|2ρ(E)
  • I(A:B)=S(A)+S(B)S(AB)
  • Bell states |ψ±
  • CNOT =|00|I+|11|X
  • ρ˙=i[H,ρ]+𝒟[L]ρ
  • [ϕ(x),π(y)]=iδ(xy)
  • (+m2)ϕ=0
  • Z=Tr(eβH)

4. Wave Packet spreading example

Free particle dispersion: σx(t)=σx(0)1+(t2mσx(0)2)2 → Used in cold-atom clouds, ultrafast electron microscopy.

Two-level Rabi oscillation

Population oscillation: Pe(t)=sin2(Ωt/2) → Atomic clocks, qubit control.

Harmonic oscillator example

Ground state energy: E0=12ω → Zero-point fluctuations in quantum optics.

Formula Description Applications
itΨ=H^Ψ Time-dependent Schrödinger equation Dynamics, atoms, molecules
H^ψ=Eψ Time-independent Schrödinger equation Spectra, tunneling, bound states
ΔxΔp2 Heisenberg uncertainty Measurement limits, wave packets
[x,p]=i Canonical commutator Quantization, oscillators
A=ψ|A|ψ Expectation value Predictions, statistics
P(a)=|a|ψ|2 Born rule Measurement probabilities
U^(t)=eiHt/ Time-evolution operator Quantum gates, scattering
ρ=ipi|ψiψi| Density matrix Decoherence, open systems
S=Tr(ρlogρ) von Neumann entropy Entanglement, thermodynamics
Tr(ρA) Expectation via density matrix Ensembles, thermal states
dρdt=i[H,ρ]+k𝒟[Lk]ρ Lindblad master eq. Decoherence, dissipation
𝒟[L]ρ=LρL12{LL,ρ} Dissipator Relaxation, noise
Z=Tr(eβH) Partition function Thermodynamics, blackbody
ψ(x)=12πdpeipx/ϕ(p) Fourier relation Wavepackets, scattering
j=2mi(ψ*ψψψ*) Probability current Continuity, tunneling
a^=12mω(mωx+ip) Annihilation operator QHO, quantum optics
En=ω(n+12) HO spectrum Phonons, cavities
ϕn(x)= HO eigenfunctions Basis for perturbation theory
H^spin=γ𝐁𝐒 Spin Hamiltonian NMR, ESR, qubits
χ(ω)=0dteiωtC(t) Response function Conductivity, noise
k=2mE/ Free-particle wavenumber Beams, dispersion
ψ(x)=ncnϕn(x) Basis expansion Computation, spectral theory
H=H0+λV Perturbation theory split Approximations, resonances
En(1)=n|V|n 1st-order energy shift Stark, Zeeman effects
Γ=2π|f|V|i|2ρ(Ef) Fermi golden rule Transition rates
(a|b)=Tr(ab) Hilbert-Schmidt inner product Superoperators, channels
Φ(ρ)=kAkρAk CPTP map (quantum channel) Noise, quantum info
I(A:B)=S(A)+S(B)S(AB) Mutual information Correlations, QIT
|ψ±=12(|01±|10) Bell states Entanglement, teleportation
UCNOT=|00|I+|11|X CNOT gate Quantum computing
[ϕ(x),π(y)]=iδ(xy) Canonical QFT commutator Field quantization
E2=p2c2+m2c4 Relativistic dispersion QFT, particles
=ψ¯(iγμμm)ψ Dirac Lagrangian Fermions, QED
ϕ+m2ϕ=0 Klein-Gordon eq. Bosons, relativistic waves

See also

Table of contents (198 articles)

Index

Full contents

9. Quantum optics and experiments (5) Back to index
Experimental quantum physics: qubits, dilution refrigerators, quantum communication, and laboratory systems.
Experimental quantum physics: qubits, dilution refrigerators, quantum communication, and laboratory systems.
14. Plasma and fusion physics (8) Back to index
Conceptual illustration of plasma physics in a fusion context, showing magnetically confined ionized gas in a tokamak and the collective behavior governed by electromagnetic fields and transport processes.
Conceptual illustration of plasma physics in a fusion context, showing magnetically confined ionized gas in a tokamak and the collective behavior governed by electromagnetic fields and transport processes.

References


Author: Harold Foppele