Conditions governing the generalisation of threshold bound states by N attractive delta potentials in one and three dimensions

• Authors: Marappan Dharani , Basudeb Sahu , Chakrakodi Shastry
• Languages of publication: EN

Abstracts

EN

This paper proves that for N attractive delta function potentials the number of bound states (Nb) satisfies 1 ≤ N
b ≤ N in one dimension (1D), and is 0 ≤ N
b ≤ N in three dimensions (3D). Algebraic equations are obtained to evaluate the bound states generated by N attractive delta potentials. In particular, in the case of N attractive delta function potentials having same separation a between adjacent wells and having the same strength λV, the parameter g=λVa governs the number of bound states. For a given N in the range 1–7, both in 1D and 3D cases the numerical values of gn, where n=1,2,..N are obtained. When g=gn, Nb ≤ n where Nb includes one threshold energy bound state. Furthermore, gn are the roots of the Nth order polynomial equations with integer coefficients. Based on our numerical calculations up to N=40, even when N becomes large, 0 ≤ g
n ≤ 4 and $\frac{{\Sigma g_n }}
{N} \simeq 2
$ and this result is expected to be generally valid. Thus, for g > 4 there will be no threshold or zero energy bound state, and if g≈ 2 for a given large N, the number of bound states will be approximately N/2. The empirical formula gn = 4/[1+exp((N
0 − n)/β)] gives a good description of the variation of gn as a function of n. This formula is useful in estimating the number of bound states for any N and g both in 1D and 3D cases.

Keywords

EN

delta potential; bound states; scattering; thresold energy

• Publisher: De Gruyter Open
• Journal: Open Physics
• Year: 2013
• Volume: 11
• Issue: 8
• Pages: 995-1005

Dates

published

1 - 8 - 2013

online

23 - 10 - 2013

Contributors

author

Marappan Dharani

• Department of Physics, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Bangalore, 560035, India

author

Basudeb Sahu

• Department of Physics, North Orissa University, Baripada, 757003, India

author

Chakrakodi Shastry

• Department of Physics, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Bangalore, 560035, India

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Identifiers

DOI

10.2478/s11534-013-0259-4