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Computer Program Detail Page

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written by Wolfgang Christian
The Eigenstate Superposition model illustrates the fundamental building blocks of one-dimensional quantum mechanics, the energy eigenfunctions  ψn(x) and energy eigenvalues En.  The user enters the expansion coefficients into a table and the simulation uses the superposition principle to construct and display a time-dependent wave function using either infinite square well (ISW) or simple harmonic oscillator (SHO) eigenfunctions.

The Eigenstate Superposition model was created using the Easy Java Simulations (EJS) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the ejs_qm_Superposition.jar file will run the program if Java is installed.

Please note that this resource requires at least version 1.5 of Java (JRE).
View the source code document attached to this resource
Subjects Levels Resource Types
General Physics
- Computational Physics
Quantum Physics
- Bound State Systems
- General
- Upper Undergraduate
- Instructional Material
= Interactive Simulation
= Tutorial
Intended Users Formats Ratings
- Educators
- Learners
- application/java
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© 2008 Wolfgang Christian
infinite square well, quantum mechanics, simple harmonic oscillator, superposition principle
Record Creator:
Metadata instance created August 30, 2008 by Wolfgang Christian
Record Updated:
June 4, 2014 by Andreu Glasmann
Last Update
when Cataloged:
August 31, 2008
Other Collections:

Zeeman Effect

Author: MuckrakerW M
Posted: October 25, 2014 at 8:08AM
Source: The Quantum Exchange collection

There are applets or even software that simulates the Zeeman Effect but I cannot find anything at all at this particular website which uses Ejs to create physics applets for use by scientists primarily illustrating Zeeman's effect. Anyone know why this is so?

» reply

Eigenstate Superposition Simulation

Author: MuckrakerW M
Posted: October 20, 2014 at 9:38PM
Source: The Quantum Exchange collection

The ejs simulator certainly helps you to get a better understanding of how to compute the eigenfunctions and their corresponding eigenvalues. But this is done when you normalize the wave function, which, in order to be normalized must be square integrable and finite. Then you can observe depending on quantum number n the various energy eigenfunctions and values in the 1-d infinite square well as they oscillate at different wavelengths and amplitudes you can set again depending on your bounds, i.e. -a < x < a. Moreover that you do all this because the eigenfunctions are standing waves in a bound state and not traveling waves.

On the other hand, the harmonic oscillator is a bit different. That is, one must realize using such wave functions to solve the Schrodinger equation would not be so easy to do because of several problems that develop. One such being the quadratic x^2 and switching the constant -hbar/2m away from y'' in order to make it have a coefficient of one since it is the highest order derivative in the differential equation.

To make life a whole lot simpler we have to use the Hermite polynomials for the SHO which are not hard at all. For the most part if you know how to do power series in calculus then it is relatively easy to find solutions to the S.E. using Hermite polynomials and their recurrent relation from the Hermite differential equation.

» reply

Re: Eigenstate Superposition Simulation

Author: Bruce, ComPADRE Dir
Posted: Oct 20, 2014 at 10:46PM

Thank you for your comment. This is true, the Superposition Model uses the simple harmonic oscillator wavefunctions using the Hermite Polynomials, as outlined in the description.

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AIP Format
W. Christian, Computer Program EIGENSTATE SUPERPOSITION MODEL (2008), WWW Document, (
W. Christian, Computer Program EIGENSTATE SUPERPOSITION MODEL (2008), <>.
APA Format
Christian, W. (2008). Eigenstate Superposition Model [Computer software]. Retrieved November 1, 2014, from
Chicago Format
Christian, Wolfgang. "Eigenstate Superposition Model." (accessed 1 November 2014).
MLA Format
Christian, Wolfgang. Eigenstate Superposition Model. Computer software. 2008. Java (JRE) 1.5. 1 Nov. 2014 <>.
BibTeX Export Format
@misc{ Author = "Wolfgang Christian", Title = {Eigenstate Superposition Model}, Month = {August}, Year = {2008} }
Refer Export Format

%A Wolfgang Christian
%T Eigenstate Superposition Model
%D August 31, 2008
%O application/java

EndNote Export Format

%0 Computer Program
%A Christian, Wolfgang
%D August 31, 2008
%T Eigenstate Superposition Model
%8 August 31, 2008

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