Summary
Then-channels-wave radial Sohrödinger equation is transformed into a Riccati equation for a matrix functionS(K, r) which approaches theS-niatrix asymptotically asr→ ∞. It is pointed out that under rather general conditions, S(K, r) is completely determined by a single functionf(K, r) which approaches the Fredholm determinant asr→∞ The problem of parametrization ofS(K, r) is briefly discussed, and, by making use of the algebraic relations betweenS(K, r) andf(K, r), the two-ohannel problem is reduced to the solution of three coupled first-order equations for three real bounded parameters which determine the (S-matrix. These equations are especially convenient for numerical computations.
Riassunto
Si trasforma l’equazione di Schrödinger radiale dell’onda * nel canalen in una equazione di Riceati per una funzione di matrice S(K, r) che approssima la matriceS asintoticamente quandor→∞. Si mette in evidenza che, entro condizioni abbastanza generali, S(K, r) è completamente determinata da una funzionef(K, r) singola che approssima il déterminante di Fredholm quandor→∞. Si discute brevemente il problema della parametrizzazione diS(K, r) e, facendo uso delle relazioni algebriche fraS(K, r) e f(K., r), si riduce il problema di due canali alia soluzione di tre equazioni di primo ordine accoppiate di tre parametri limitati reali che determinano la matriceS. Queste equazioni sono specialmente utili nei caleoli numerici.
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References
F. Calogero:Nuovo Cimento,27, 261 (1963).
P. M. Morse andW. P. Allis:Phys. Rev.,44, 269 (1933).
Other papers with a similar approach to the many-channel problem include:G. J. Kynch:Proc. Phys. Soc. (London), A 65, 83 (1952);G. Zemach:Nuovo Cimento,33, 939 (1964).
G., T. Kynch:lac cit.
Tlie two-channel problem considered here is, for energies above the secondchannel threshold, rather similar mathematically to the problem of the scattering of two spin one-half particles which are coupled by a tensor force. The latter problem has been considered from the point of view of this paper [J. R. Cox andA. Perlmutter:Nuovo Cimento (to be published)], and sample numerical calculations were carried out.
E. G. Newton:Journ. Math. Phys.,2, 188 (1960).
The superscript «T » and prime always indicate the matrix transpose and differentiation with respect tor, respectively.
Also seeK. J. Le Couteuk: Proc.Roy. Soc, A256, 115 (1960).
N. Levinson:Kgl. Danslce Vid. Sels., Mat.-Fys. Medd.,25, no. 9 (1949).
See, for example,J. R. Cox:Ph. B. Thesis, Indiana University (1962), unpublished.
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Cox, J.R. On the computation of the many-channelS- matrix. Nuovo Cim 37, 474–491 (1965). https://doi.org/10.1007/BF02749850
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DOI: https://doi.org/10.1007/BF02749850