Abstract
The completeness relation for the eigenfunctions of a self-adjoint operator generally involves a divergent series or integral. In this paper, we show, using the eigenfunctions of the infinite square well as an example, that these divergent objects can be interpreted as distributions. This should be obvious since the right-hand side of these completeness relations is the Dirac delta function but the direct calculation of the right-hand side can be very laborious, but instructive.
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14 March 2022
A Correction to this paper has been published: https://doi.org/10.1007/s13538-022-01078-8
References
E. Merzbacher, Quantum Mechanics, Third Edition. (John Wiley and Sons, Inc. Hoboken, 1997) p. 206
J. D. Jackson, Mathematical Methods for Quantum Mechanics (A. Benjamin, New York, 1962) p. 30
G. Barton, Elements of Green’s Functions and Propagation (Clarendon Press, Oxford Page, 1989), p. 27
A.H. Zemanian, Orthogonal Series Expansions of Certain Distributions and the Distribution Transform Calculus. J. Math. Anal. Appl. 14, 263–275 (1966)
A.H. Zemanian, Generalized Integral Transforms, Chapter 9 (Dover, New York, 1987)
J.N. Pandey, R.S. Pathak, Eigenfunction Expansions of Generalized Function. Nagoya Math. J. 72, 1–25 (1978)
C.L.R. Braga, M. Schönberg, An. Acad. Bras. Ci. 31, 333 (1959). The authors will send copies of the relevant pages to interested readers
C.M. Bender, D.C. Brody, M.F. Parry, Am. J. Phys. 88, 148 (2020)
P.A.M. Dirac, Quantum Mechanics (Cambridge University Press, Cambridge, 1935)
L. Schwartz, Theory of Distributions, (Herman, Paris, 1950)
G. Temple, Theories and Applications of generalized functions. J. Lond. Math. Soc. 28, 175–148 (1953)
G. Temple, The theory of generalized functions. Proc. R. Soc. Lond. A 228, 175–190 (1955)
J.M. Aguirregabiria, N. Rivas, \(\delta\)-functions converging sequences Am. J. Phys. 70, 180–185 (2002)
T. Sucher, Distributions, Fourier Transforms and Some of Their Applications to Physics (World Scientific, Singapore, 1991)
S. Vincenzo, C. Sanches, Can. J. Phys. 88, 809 (2010)
R.S. Strichartz, A Guide to Distribution Theory and Fourier Transforms (World Scientific, Singapore, 2003), pp. 101–108
M.J. Lichthill, Introduction to Fourier Analysis and Generalized Functions (Cambridge University Press, Cambridge, 1964) p. 29
A.M. Peremolov, Y.B. Zel’dovich, Quantum Mechanics – Selected Topics (World Scientific, Singapore, 1998) p. 55
C.L.R. Braga, Notas de Física Matemática (Edusp, São Paulo, 2006) p. 165. The authors will send copies of the relevant pages to interested readers
K.R. Brownstein, Am. J. Phys. 43, 173 (1975)
M. Amaku, F.A.B.M. Coutinho, F.M. Toyama, Rev. Bras. Ens. Fis. 42, e20190099 (2020)
T.M. Apostol, Mathematical Analysis, 2nd edition (Addison-Wesley, Menlo Park, 1974) p. 285
L, Schwartz, Mathematics for the Physical Sciences (Addison-Wesley, Massachussets, 1966)
D.J. Griffiths, Introduction to Quantum Mechanics, second edition (Pearson Education Inc. London, 2005) p. 33
F.A.B. Coutinho, Y. Nogami, J.F. Perez, Generalized point interactions in one-dimensional quantum mechanics. J. Phys A Math Gen. 30, 3937–3945 (1997)
F.A.B. Coutinho, The role of boundary conditions in specifying the system: Comment on a comment by Cisneros et al. Am. J. Phys. 75 (10, 953–955 2007. Am. J. Phys. 76, 588 (2008)
V.S. Araujo, F.A.B. Coutinho, J. Fernando Perez, Operator domains and self-adjoint operators. Am. J. Phys. 72, 203-213 (2004)
G. Bonneau, J. Farant, G. Valent, Self-adjoint extensions of operators and the teaching of quantum mechanics, Am. J. Phys. 69, 322–331 (2001)
M. Calçada, J.T. Lunardi, L.A. Manzoni, W. Monteiro, Distributional approach to point interactions in one-dimensional quantum mechanics. Front. Phys. 2, 1–10 (2014)
M. Calçada, J.T. Lunardi, W. Monteiro, M. Pereira, A distributional approach for the One- Dimensional Hydrogen Atom. Front. Phys. 7, 101 (2019)
M. Schechter, Operator Methods in Quantum Mechanics (North Holland New York, 1981) p. 235-236
S. De Vincenzo, Impenetrable Barriers in Quantum Mechanics. Rev. Mex. Fis. 54, 1–6 (2008)
Acknowledgements
The authors would like to thank Professors Luiz Nunes de Oliveira and Walter Felipe Wreszinski for discussions and clarifications about the content of this paper. The authors acknowledge partial financial support from CNPq.
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Amaku, M., Coutinho, F.A.B., Éboli, O.J.P. et al. Some Problems with the Dirac Delta Function: Divergent Series in Physics. Braz J Phys 51, 1324–1332 (2021). https://doi.org/10.1007/s13538-021-00916-5
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DOI: https://doi.org/10.1007/s13538-021-00916-5