perturbation theory

American  

noun

1. a mathematical framework for finding an approximate solution to an extremely difficult or unsolvable problem by starting with the exact solution of a similar but less difficult problem.

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perturbation theory Scientific  

1. A set of mathematical methods for obtaining approximate solutions to complex equations for which no exact solution is possible or known, generally involving an iterative algorithm in which each new term contributing to the solution has less significance than the last. In quantum physics, Feynman diagrams are used to calculate the terms for the perturbation theory solution of interactions between particles.

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Example Sentences

"Standard computational studies of photocatalysts typically focus on ground-state properties and neglect excited-state effects, despite the fact that photocatalysis is inherently driven by photoexcited charge carriers. Specifically, we employ many-body perturbation theory methods."

From Science Daily • Mar. 16, 2026