##  [WKB Approximation](/wkb-approximation) 

  ##  [WKB Approximation](https://quantummech.quantumdictionary.io/wkb-approximation-1) 

  

 [![Quantum Mechanics Dictionary](/sites/default/files/styles/large/public/2026-01/Quantum%20Mechanics.png.webp?itok=tC_FGCW0)](/topic-specific-dictionaries/modern-physics/quantum-mechanics)

- Modern Physics -

**Quantum Mechanics Dictionary**

 







 

 

 

 



 

 

 

 

Definition

An approximation and alternative-formalism concept defining methods for computing quantum predictions when exact solutions are impractical. It governs controlled expansions, action-based formulations, and phase-space representations that support analytic and numerical work. It does not ensure accuracy outside its regime of validity and requires explicit error assessment or convergence checks.



 

 

 

 

 





 

 



 ##  [WKB Approximation](https://natural.quantumdictionary.io/wkb-approximation-0) 

  

 [![Natural & Formal Sciences Dictionary](/sites/default/files/styles/large/public/2026-01/Natural%20%26%20Formal%20Sciences.png.webp?itok=2kCDRVQv)](/topic-specific-dictionaries/natural-formal-sciences)



**Natural & Formal Sciences Dictionary**

 







 

 

 

 



 

 

 

 

Definition

A semiclassical asymptotic method that constructs approximate solutions to linear differential equations with a small parameter multiplying the highest derivative by expanding the logarithm of the solution (the action) in powers of the small parameter.