Skip to main content
University Quantum Mechanics I

University Quantum Mechanics I · The Quantum Harmonic Oscillator · 9.02

Dimensionless form and the Gaussian that survives at large x

Put ξ = x √(m ω / ℏ) and measure E in units of ℏ ω / 2, so ε = 2E / ℏ omega and the equation is ψ'' = (ξ² - ε) ψ.

Course-map guide · not a complete lesson or simulation

Scope & orientation

What this subsection covers

Put ξ = x √(m ω / ℏ) and measure E in units of ℏ ω / 2, so ε = 2E / ℏ omega and the equation is ψ'' = (ξ² - ε) ψ.

A strong response uses ψₙ and |ψₙ|² with nodes marked and states where the model stops being reliable.

Reasoning checklist

Evidence, assumptions and limits

01

Assumptions to state

State the system, observable, approximation, and conditions held fixed before using a model.

02

Evidence to collect

Do the vibrational band spacings of iodine vapour stay constant, as an exactly quadratic potential requires, or converge towards a dissociation limit?

Read the complete note

Do the vibrational band spacings of iodine vapour stay constant, as an exactly quadratic potential requires, or converge towards a dissociation limit? Useful evidence includes calibrated band positions, spacings plotted against quantum number, a Birge-Sponer extrapolation to the dissociation energy, an anharmonicity constant with uncertainty, and the level where equal spacing stops fitting..

03

Limits to state

This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus.

Read the complete note

This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus. It is a first dedicated quantum-mechanics course, distinct from University Physics V, which covers quantum mechanics alongside atomic, nuclear and particle physics in twenty units: this course is narrower, slower, and teaches the linear algebra it needs rather than assuming it. Hydrogen appears here as an introduction, with the full radial derivation belonging to a second course. A midterm examination is assumed around week 8. Follow your institution's published scope, notation, laboratory programme, and assessment rules. A result should be checked against units, signs, limiting cases, and the conditions under which its model was derived.

Diagram & examples

Work the claim before choosing an equation

Interactive concept map

Follow the model from claim to evidence.

01 · Physical claimDimensionless form and the Gaussian that survives at large x

Put ξ = x √(m ω / ℏ) and measure E in units of ℏ ω / 2, so ε = 2E / ℏ omega and the equation is ψ'' = (ξ² - ε) ψ.

Read the complete note

Put ξ = x √(m ω / ℏ) and measure E in units of ℏ ω / 2, so ε = 2E / ℏ omega and the equation is ψ'' = (ξ² - ε) ψ. Large xi forces exp(± ξ²/2). Writing ψ = h(ξ) exp(−ξ²/2) costs nothing - it merely defines h - and the asymptotics say only that h must not itself grow like exp(+ξ²) if ψ is to normalise.

02 · RepresentationThe subsection's claim

Model, evidence, and boundary

03 · TestPrediction before measurement

When should a model used for Dimensionless form and the Gaussian that survives at large x be revised?

04 · Evidence & boundaryDecide, then qualify

Do the vibrational band spacings of iodine vapour stay constant, as an exactly quadratic potential requires, or converge towards a dissociation limit?

Read the complete note

Do the vibrational band spacings of iodine vapour stay constant, as an exactly quadratic potential requires, or converge towards a dissociation limit? Useful evidence includes calibrated band positions, spacings plotted against quantum number, a Birge-Sponer extrapolation to the dissociation energy, an anharmonicity constant with uncertainty, and the level where equal spacing stops fitting..

Interactive diagram for Dimensionless form and the Gaussian that survives at large x: follow the physical claim through its representation, proposed test, evidence, and model boundary.

modelModel, evidence, and boundary turns the stated idea into a representation that can make a prediction.

Example questions

Try the reasoning before revealing the structure.

Diagram check

When should a model used for Dimensionless form and the Gaussian that survives at large x be revised?

Quick check

Test the reasoning, not recall

When should a model used for Dimensionless form and the Gaussian that survives at large x be revised?

Choose an answer to test the model.