{"title":"通过求三次方程的实根求平方量子阱超越方程的近似解。","authors":"J. Noël, L. Levesque","doi":"10.1139/cjp-2023-0004","DOIUrl":null,"url":null,"abstract":"The energy eigenvalues En in finite square quantum wells (SQW) cannot be found using an analytic expression. As a result, numerical methods are normally used to find the eigenvalues from a transcendental equation. In this report, it will be shown that the eigenvalue solution for a given state consists in finding the only real positive root of a depressed trinomial polynomial of third order, which is as easy to solve as a quadratic equation. The method proposed can also be applied for semi-infinite, finite and asymmetric SQW, which are often presented in Quantum Mechanics (QM) textbooks at the undergraduate level. The proposed method can be applied during an exam when programmable calculators are not allowed as the real root of the trinomial polynomial can be found using the formula for the cubic equation found nearly 500 years ago.","PeriodicalId":9413,"journal":{"name":"Canadian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":1.1000,"publicationDate":"2023-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Approximate solutions of the transcendental equation for the square quantum wells by finding the real root of the cubic equation.\",\"authors\":\"J. Noël, L. Levesque\",\"doi\":\"10.1139/cjp-2023-0004\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The energy eigenvalues En in finite square quantum wells (SQW) cannot be found using an analytic expression. As a result, numerical methods are normally used to find the eigenvalues from a transcendental equation. In this report, it will be shown that the eigenvalue solution for a given state consists in finding the only real positive root of a depressed trinomial polynomial of third order, which is as easy to solve as a quadratic equation. The method proposed can also be applied for semi-infinite, finite and asymmetric SQW, which are often presented in Quantum Mechanics (QM) textbooks at the undergraduate level. The proposed method can be applied during an exam when programmable calculators are not allowed as the real root of the trinomial polynomial can be found using the formula for the cubic equation found nearly 500 years ago.\",\"PeriodicalId\":9413,\"journal\":{\"name\":\"Canadian Journal of Physics\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.1000,\"publicationDate\":\"2023-04-14\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Canadian Journal of Physics\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.1139/cjp-2023-0004\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"PHYSICS, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Canadian Journal of Physics","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1139/cjp-2023-0004","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"PHYSICS, MULTIDISCIPLINARY","Score":null,"Total":0}
Approximate solutions of the transcendental equation for the square quantum wells by finding the real root of the cubic equation.
The energy eigenvalues En in finite square quantum wells (SQW) cannot be found using an analytic expression. As a result, numerical methods are normally used to find the eigenvalues from a transcendental equation. In this report, it will be shown that the eigenvalue solution for a given state consists in finding the only real positive root of a depressed trinomial polynomial of third order, which is as easy to solve as a quadratic equation. The method proposed can also be applied for semi-infinite, finite and asymmetric SQW, which are often presented in Quantum Mechanics (QM) textbooks at the undergraduate level. The proposed method can be applied during an exam when programmable calculators are not allowed as the real root of the trinomial polynomial can be found using the formula for the cubic equation found nearly 500 years ago.
期刊介绍:
The Canadian Journal of Physics publishes research articles, rapid communications, and review articles that report significant advances in research in physics, including atomic and molecular physics; condensed matter; elementary particles and fields; nuclear physics; gases, fluid dynamics, and plasmas; electromagnetism and optics; mathematical physics; interdisciplinary, classical, and applied physics; relativity and cosmology; physics education research; statistical mechanics and thermodynamics; quantum physics and quantum computing; gravitation and string theory; biophysics; aeronomy and space physics; and astrophysics.