How to solve generalised eigenvalue problems?

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SUMMARY

This discussion focuses on solving generalized eigenvalue problems in quantum mechanics, emphasizing the desire to develop a custom algorithm for educational purposes. The participant acknowledges the complexity of continuous sets, which often require solving coupled partial differential equations, as opposed to simpler discrete cases. Recommendations include studying the time-independent Schrödinger equation, which is an eigenvalue equation, and exploring LAPACK for its generalized eigenvalue routines and associated methodologies.

PREREQUISITES
  • Understanding of linear algebra concepts, particularly eigenvalues and eigenvectors.
  • Familiarity with partial differential equations and their applications in quantum mechanics.
  • Basic knowledge of perturbation theory in quantum mechanics.
  • Experience with numerical libraries such as LAPACK for algorithm implementation.
NEXT STEPS
  • Study the time-independent Schrödinger equation and its role in quantum mechanics.
  • Learn about LAPACK's generalized eigenvalue routines and their underlying algorithms.
  • Research coupled partial differential equations and methods for their numerical solutions.
  • Explore perturbation theory and its applications in solving eigenvalue problems.
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Physicists, mathematicians, and computer scientists interested in developing custom algorithms for solving generalized eigenvalue problems, particularly in the context of quantum mechanics.

ngkamsengpeter
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I want to write myself a algorithm to solve generalised eigenvalue problems in quantum mechanics.I know there are a lot of library there that allow me to use it directly but i just want to write my own so that i can learn the mathematics methods that solve the problem...
I don't know how to solve the generalised eigenvalue problems without using existing library in computer...
So anyone has any reference so that i can learn the mathematical methods that solve the generalised eigen value problems??
 
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For discrete sets it is easy, e.g. for spin, then you just do a matrix representation for it and solve its eigenvalue problem, this is done in all introductory linear algebra books and scientific computing books.

For the continuous set, it is more complicated. One has to, in general, solve coupled partial differential equation, which is also outlined in any introductory book in scientific computing.

Please tell us about your background in physics, math and computing and what your aim with all this is maybe we can help you better.

cheers
 
It's not simple to solve any general eigenvalue equation, indeed, the time independent Schroedinger equation is in fact an Eigenvalue equation (for the energy-eigenvalues), and only a handful of cases are analytically solvable. A lot of the time, you need to resort to approximations, such as perturbation theory.
 
Take a look at LAPACK and see if they report the source of their algorithms for their generalized eigenvalue routines. The manual gives a description of the general method and they have an extensive bibliography at the end.
 
Time reversal invariant Hamiltonians must satisfy ##[H,\Theta]=0## where ##\Theta## is time reversal operator. However, in some texts (for example see Many-body Quantum Theory in Condensed Matter Physics an introduction, HENRIK BRUUS and KARSTEN FLENSBERG, Corrected version: 14 January 2016, section 7.1.4) the time reversal invariant condition is introduced as ##H=H^*##. How these two conditions are identical?

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