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Calcimator

Schrodinger Equation Calculator

Calculate energy eigenvalues, wave functions, and quantum states for infinite wells and harmonic oscillators.

About this calculator

This calculator solves the time-independent Schrodinger equation for two standard textbook potentials, chosen via Potential Type. For the Infinite Square Well (a particle confined between impenetrable walls), Energy (Eₙ) follows Eₙ = n²π²ℏ²/(2mL²) -- it grows with the SQUARE of Quantum Number (n) and shrinks with the square of both Well Width / Char. Length (L) and Particle Mass (m), which is why quantum confinement effects only show up at atomic-scale widths. For the Harmonic Oscillator, the calculator treats Well Width / Char.

Length AS the oscillator's characteristic length x0, solving x0 = sqrt(ℏ/(mω)) backwards for angular frequency rather than asking for a spring constant directly, giving Eₙ = (n − 1/2)ℏω with Quantum Number (n) starting at 1 for the ground state -- matching the well's own n=1 convention rather than the oscillator's usual v=0 ground-state label. Number of Nodes always equals Quantum Number (n) − 1 in EITHER potential: the ground state (n=1) has zero nodes and each higher state adds exactly one, independent of Particle Mass or Well Width / Char. Length -- node count is a topological property of the wavefunction shape, not its energy. Wavelength (λₙ) and Momentum (pₙ) describe the particle's own de Broglie matter wave inside the well or oscillator, not a photon; Transition Frequency is instead the frequency of a photon that would be absorbed or emitted jumping to the next level, derived from Energy to Next Level.

Inputs

m
kg

Results

Energy (Eₙ)

37.61 eV

Energy to Next Level

112.83 eV

Wavelength (λₙ)

0 m

Momentum (pₙ)0 kg·m/s
Transition Frequency27,280,000,000,000,000 Hz
Number of Nodes0
Probability Density at Center20,000,000,000 m⁻¹
How to Use This Calculator
  1. Enter Quantum Number (n): 1 is the ground state, higher values give excited states with more nodes.
  2. Select Potential Type: Infinite Square Well (particle in a box) or Harmonic Oscillator (equally spaced levels).
  3. Enter Well Width / Characteristic Length (m): atomic wells are ~1e-10 m (1 Å); quantum dots are ~10–100 nm.
  4. Set Particle Mass (kg): default is the electron mass (9.109e-31 kg).
  5. Read Energy (Eₙ) in eV, Wavelength (λₙ), and Number of Nodes — the ground state has zero nodes, n-th state has n−1 nodes.

How the result changes with Well Width / Char. Length

Well Width / Char. LengthEnergy (Eₙ)Energy to Next LevelWavelength (λₙ)
0150.44 eV451.33 eV0 m
066.86 eV200.59 eV0 m
016.72 eV50.15 eV0 m
06.02 eV18.05 eV0 m

What each input means

Quantum Number (n)
Principal quantum number
Potential Type
Type of confining potential
Well Width / Char. Length
Width of well or characteristic length
Particle Mass
Mass of the particle (default: electron)

What each result means

Probability Density at Center
Probability density |ψ(L/2)|² at the well's midpoint (infinite square well only; 0 for the harmonic oscillator, which this calculator does not compute separately).

How this is calculated

Formula

Eₙ = n²π²ℏ² / (2mL²)

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Quantum Number (n) = 1, Potential Type = 0, Well Width / Char. Length = 1e-10, Particle Mass = 9.109e-31 = 4 input(s) provided
  2. Calculate Energy
    Energy = Number(energyEV.toExponential(4))
    37.611 = 37.611
  3. Calculate Energy to Next Level
    Energy to Next Level = Number(energySpacing.toExponential(4))
    112.83 = 112.83
  4. Calculate Wavelength
    Wavelength = Number(wavelength.toExponential(3))
    2e-10 = 2e-10
  5. Calculate Momentum
    Momentum = Number(momentum.toExponential(3))
    3.313e-24 = 3.313e-24
  6. Calculate Transition Frequency
    Transition Frequency = Number(transitionFrequency.toExponential(3))
    27280000000000000 = 27280000000000000
  7. Calculate Probability Density at Center
    Probability Density at Center = (2/L) x sin²(nπ/2)
    20000000000 = 20000000000

Engine last updated . Checked against 6 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.

Frequently Asked Questions

Why does raising Particle Mass always lower Energy (Eₙ), in both potential types?

Both formulas put mass in the denominator: the infinite well's Eₙ = n²π²ℏ²/(2mL²) and the harmonic oscillator's Eₙ = (n − 1/2)ℏω (where ω itself is inversely proportional to mass through ω = ℏ/(mL²)) both shrink as Particle Mass grows. Physically, a heavier particle needs less kinetic energy to have the same de Broglie wavelength fit inside the same confinement, so its quantized energy levels sit closer together and lower overall.

Why does Number of Nodes only depend on Quantum Number (n), not Particle Mass or Well Width?

Number of Nodes counts how many times the wavefunction crosses zero inside the well or oscillator, and that count is a purely topological property of the quantum state -- the ground state (n=1) always has zero nodes and every higher state adds exactly one, in both potentials modeled here. Particle Mass and Well Width / Char. Length change the ENERGY of each level, not how many times its wavefunction oscillates.

What does the Harmonic Oscillator branch do with Well Width / Char. Length, since there's no spring-constant input?

It reuses that field as the oscillator's characteristic length x0, and solves the standard relation x0 = sqrt(ℏ/(mω)) backwards for angular frequency ω, instead of asking for a spring constant directly. This keeps the same two physical inputs -- mass and a length -- meaningful across both potential types, at the cost of not letting you set stiffness and mass independently the way a real spring-mass system would.

Why does Quantum Number (n) start at 1 for the harmonic oscillator instead of the usual n=0 ground state?

This calculator keeps one Quantum Number (n) input that starts at 1 for BOTH potential types, so the harmonic oscillator branch computes energy as (n − 1/2)ℏω rather than the textbook (v + 1/2)ℏω with v starting at 0. Entering n=1 still gives the true ground-state energy of ℏω/2 -- it's labeled with the well's n=1 convention instead of the oscillator's own v=0 convention, so the two branches share one input scale.

Is Wavelength (λₙ) the color of light this system would emit?

No -- Wavelength (λₙ) is the particle's own de Broglie matter wavelength at that energy level, not a photon's wavelength. The photon emitted or absorbed in a transition between levels is described instead by Transition Frequency, which this calculator derives from Energy to Next Level rather than reporting a separate photon wavelength.

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