Printer Friendly

Solution of Effective-Mass Dirac Equation with Scalar-Vector and Pseudoscalar Terms for Generalized Hulthen Potential.

1. Introduction

The Hulthen potential [1] is one of the best known potentials in physics, as a short-range potential [2]. In the present work, we deal with the following form [3, 4]:

VM = [V.sub.0] [e.sup.-2[beta]x]/q[e.sup.-2[beta]x] -1, (1)

where the parameter [V.sub.0] can be written as Z(2[beta]) with the constant Z and [beta] is the screening parameter (in atomic units) [2] with deformation parameter q. The constant Z is related to the atomic number if one uses this potential in atomic physics. Basically, the Hulthen potential is a special form of the Eckart potential [2, 5].

As a short-range potential, the Hulthen potential has a great advantage because the Schrodinger equation can be solved exactly for this potential with l = 0. With this advantage, the Hulthen potential has been used in different areas of physics, such as in solid-state physics [6], nuclear and particle physics [7], atomic physics [8], and chemical physics [9], and investigated with various techniques [2,10-17].

In this work, we search the bound state solutions of the generalized Hultheen potential which can be written also in a complex form identifying the PT-symmetric case in a closed form for the case where the mass depends on spatial coordinate and extend the Dirac equation including the scalar, vector, and pseudoscalar interaction terms to this case. After the works byVon Roos [18], and Levy-Leblond [19], the solutions of relativistic and nonrelativistic wave equations with a position-dependent mass have received great attention in literature [3, references therein]. In [20], the bound state solutions of the Klein-Gordon (KG) and Dirac equations with the Hulthen potential by using the approach proposed by Biedenharn have been worked where the scattering state solutions have been also presented. In [21], the analytical results for the bound states of the Dirac equation with the generalized Hultheen potential as a tensor term have been studied within the concept of the SUSYQM. In the present work, we extend the search including the solutions of the Dirac equation having a pseudoscalar interaction term, as in [22-25], for the q-parameter Hultheen potential within the position-dependent mass (PDM) formalism. This formalism gives an opportunity such as writing the analytical results for the case where the mass is constant. This means that our results are also available for the cases where the Dirac equation has pseudospin and spin symmetry. Our generic results which will be given below makes it possible to give the "wave functions" with their normalization constants for both the cases of PDM formalism and constant mass. We search here also the analytical results for the PT-symmetric/non-Hermitian and PT-symmetric/pseudo-Hermitian form of the Hulthen potential for both of upper and lower component which are presented again within the PDM formalism. These give us also the results for the case where the mass is constant if necessary. Among the above results, because of the q-parameter in potential, we apply our results for three different forms of the potential as special cases.

The organization of this work is as follows. In Section 2, we write the Dirac equation with scalar ([V.sub.S] (x)), vector ([V.sub.V] (x)), and pseudoscalar ([V.sub.P] (x)) potentials in 1 + 1 dimension for the case where the mass is a spatially coordinate function. In Section 3, we search the bound state solutions for upper and lower component of the Dirac spinor separately and give the normalization constant. We construct a relation between the mass function and the potentials to reduce the Dirac equation to an analytically solvable form of second-order differential equation. We give also the results for the case where the mass is constant and observe that the results obtained for this case correspond to the solutions when the spin and pseudospin symmetry occur in Dirac equation. The spin symmetry appears when the difference of the scalar and vector potentials is constant; that is, [DELTA](x) = const., and the pseudospin symmetry appears when the sum of the scalar and vector potentials is constant; that is, [SIGMA](x) = const. [20,21,26]. Finally, we obtain the nonrelativistic result for the bound state solution for the generalized Hulthen potential. The present work can also be seen as an application of the parametric generalization of the Nikiforov-Uvarov method which will be given in Appendix briefly [27, 28]. In Section 4, we write the generalized Hulthen potential in a complex form which corresponds to the PT-symmetric form of the potential and find the energy levels for upper and lower component of the Dirac spinor with normalized wave functions. The PT-symmetric formulation with non-Hermitian Hamiltonians having real or complex spectra of quantum mechanics has received a great attention in literature after the work by Bender and Boettcher [29-31]. In Section 5, we collect briefly our analytical results for special values of the parameter q corresponding to the standard Hulthen potential (q = 1), to the Woods-Saxon potential (q = -1) and to the exponential potential (q = 0) while the mass depends on spatially coordinate function. We give our conclusions in Section 6.

2. Dirac Equation in 1+1 Dimension

The time-independent Dirac equation for a spin-1/2 particle subjected to scalar, vector, and pseudoscalar potentials in terms of the [SIGMA](x) = [V.sub.V] (x) + [V.sub.S] (x), and [DELTA](x) = [V.sub.V] (x) - [V.sub.S] (x) is given by([??] = c= 1) [22, 23, 32-36]

([[sigma].sub.1]p + [[sigma].sub.3]m (x) + 1 + [[sigma].sub.3]/2 [SIGMA] (x) + 1 - [[sigma].sub.3]/2 [DELTA] (x) + [[sigma].sub.2] [V.sub.p] (x)) [PSI] (x) = E[PSI] (x), (2)

where [[sigma].sub.1], [[sigma].sub.2], and [[sigma].sub.3] are the Pauli spin matrices, and we write the mass as m(x). By taking the Dirac spinor as [PSI] = [([[phi].sub.1], [[phi].sub.2]).sup.t], where t indicates the transpose, we obtain the following first-order coupled equations for upper and lower components:

- i d[[phi].sub.1] (x) /dx -[m (x) - [DELTA](x) + E] [[phi].sub.2] (x) + i[V.sub.P][[phi].sub.1] (x) = 0, (3)

- i d[[phi].sub.2] (x) /dx -[m (x) - [SIGMA](x) + E] [[phi].sub.1] (x) + i[V.sub.P][[phi].sub.2] (x) = 0. (4)

Writing [[phi].sub.2] (x) in terms of [[phi].sub.1] (x) with the help of (3) and inserting it into (4) give us

[mathematical expression not reproducible]. (5)

We write here the equality dm(x)/dx = d[DELTA](x)/dx between the mass function and the potentials to reduce the above complicated equation to a simpler one which can be solved analytically. This relation gives us also the opportunity about finding the mass function explicitly and the second-order equation for upper component [[phi].sub.1] (x) as

{[d.sup.2]/d[x.sup.2] - d[V.sub.P] (x)/dx - [V.sup.2.sub.P] (x) - [m (x) + E - [DELTA] (x)] [m (x) + [SIGMA] (x) - E]} [[phi].sub.1] (x) = 0. (6)

By following similar steps and using the equality for the mass function as dm(x)/dx = -d[SIGMA](x)/dx, we obtain the second-order equation for lower component [[phi].sub.2] (x) as

{[d.sup.2]/d[x.sup.2] + d[V.sub.P] (x)/dx - [V.sup.2.sub.P] (x)] - [m(x) + E - [DELTA] (x)] [m (x) + [SIGMA] (x) - E]} [[phi].sub.2] (x) = 0. (7)

Equations (6) and (7) can be solved by using the parametric generalization of the Nikiforov-Uvarov method which is given in Appendix briefly. In the next section, we solve the above equations for the scalar, vector, and pseudoscalar potentials by identifying them in terms of the Hulthen potential given in (1). First, we find the appropriate mass function by using the equalities, and then we write the bound state solutions with the corresponding normalized wave functions.

3. Bound States for Generalized Hulthen Potential

We are now in a position to identify the potentials in terms of the generalized Hultheen potential. We tend to write them as follows [3, 4]:

[mathematical expression not reproducible], (8)

where i = 1, 2, [V.sub.1] is for the upper component [[phi].sub.1] (x), and [V.sub.2] is for the lower component [[phi].sub.2] (x). We obtain (7) for [[phi].sub.2] (x) by replacement [V.sub.2] [left right arrow] -[V.sub.1] in (6). In addition, we can handle the explicit form of the wave function for [[phi].sub.2] (x) by doing [beta] [left right arrow] -[beta] in [[phi].sub.1] (x).

From (8), we have

[SIGMA] (x) = ([V.sub.0] - [S.sub.0]) [e.sup.-2[beta]x]/q[e.sup.-2[beta]x] - 1, [DELTA] (x) = ([V.sub.0] - [S.sub.0]) [e.sup.-2[beta]x]/q[e.sup.-2[beta]x] - 1. (9)

By using (8) and (9), we write the mass function from the equality obtained for [[phi].sub.1] (x) as m(x) = [m.sub.0] + [m.sub.1] ([e.sup.- [beta]2x]/ (q[e.sup.-2[beta]x] - 1)), where the parameter mo is basically the integral constant, and we denote it as "constant mass"; the other parameter [m.sub.1] is obtained as [m.sub.1] = [V.sub.0] + [S.sub.0]. This means that the mass parameter [m.sub.1] contains the contributions coming from vector and scalar potentials. The equality obtained for [[phi].sub.2] (x) gives us the mass function as m(x) = [m.sub.0] + [m.sub.2] ([e.sup.-2[beta]x]/(q[e.sup.-2[beta]x] -1)) with [m.sub.2] = [V.sub.0] - [S.sub.0] including the contributions coming from vector and scalar potentials. So, we can combine these two mass functions in a single form as m(x) = [m.sub.0] + [m.sub.i] ([e.sup.-2[beta]x] /(q[e.sup.- 2[beta]x] - 1)) which will be used in computation below.

By using a new variable as s = 1/(1 - q[e.sup.-2[beta]x]) (-[infinity] < x < +[infinity] [right arrow] 0 [less than or equal to] s [less than or equal to] 1), using (8)-(9), and inserting the mass function m(x),we have the following representative equation for both components:

{[d.sup.2]/d[s.sup.2] + 1 - 2s/s(1 - s) d/ds - 1/[s.sup.2](1 - [s.sup.2]) [A/4[[beta].sup.2] + 2B/4[[beta].sub.2] + C/4[[beta].sup.2] [s.sup.2]]} [[phi].sub.i] (s) = 0, (10)

where

[mathematical expression not reproducible], (11)

with

[mathematical expression not reproducible], (12)

and Q = 1/q. Equation (10) can be solved by using the parametric Nikiforov-Uvarov method. For this aim, we compare (10) with (A.1) in Appendix, and with the help of (A.3) we obtain the parameter set

[mathematical expression not reproducible]. (13)

With the help of (A.2) in Appendix, we write the energy spectrum of the Dirac equation with scalar-vector-pseudoscalar generalized Hultheen potential within the position-dependent mass formalism as

[mathematical expression not reproducible], (14)

which can be solved numerically to get the energy eigenvalues.

In order to handle the generic wave function for the upper and lower component of the Dirac spinor, we use (A.4) in Appendix which gives

[[phi].sub.i] (s) = [N.sub.i] [s.sup.[alpha]'/2] [(1 - s).sup.[beta]'/2] [P.sup.([alpha]',[beta]')] (1 - 2s), (15)

with [alpha]' = 2 [square root of ([[xi].sub.3])], [beta]' = 2 [square root of ([[xi].sub.1] - [[xi].sub.2] + [[xi].sub.3])], and the normalization constant [N.sub.i]. Let us now find the normalization constant. Using a new variable z = 1 - 2s(0 [less than or equal to] s [less than or equal to] 1 [right arrow] + 1 [less than or equal to] z [less than or equal to] -1), and writing the normalization condition [[integral].sup.+[infinity].sub.- [infinity]] [[absolute value of ([[phi].sub.i] (x))].sup.2] dx = 1 as

[[integral].sup.+1.sub.-1] [[absolute value of ([[phi].sub.i] (z))].sup.2] dz/[beta](1 - z)(1 + z) = 1. (16)

We get

[[absolute value of ([N.sub.i])].sup.2]/[beta] 1/[2.sup.[alpha]'+[beta]'] x [[integral].sup.+1.sub.-1] [(1 - z).sup.[alpha]'-1] [[[P.sup.(a',[beta]').sub.n] (z)].sup.2] dz = 1. (17)

By using the following representation of the Jacobi polynomials [22]

[mathematical expression not reproducible], (18)

and (17) is written as

[mathematical expression not reproducible], (19)

where [(n).sub.r] is the Pochhammer symbol [24]. With the help of the following integral equation including a Jacobi polynomial written in terms of the hypergeometric function [sub.3][F.sub.2] (-n, a, b; c, d; y) [24]

[mathematical expression not reproducible], (20)

with the conditions Re [rho] > -1 and Re [sigma] > -1; the normalization constant is computed

[N.sub.i] = [square root of ([GAMMA]'[GAMMA]")], (21)

where

[mathematical expression not reproducible]. (22)

The condition to be satisfied in (20) gives an upper limit for l as l < A/[beta] which can be used to determine the greatest integer value for the quantum number n as n < [A/[beta]].

We obtain the formal analytical solutions for the problem under consideration giving the results in terms of representative equations (14) and (15). Now we move on to consider the upper and lower components of the Dirac spinor separately and summarize the results for the case where the mass is constant and the case of nonrelativistic limit for the present problem.

3.1. Results. For the upper component (i = 1), we write the potential parameter as [m.sub.1] = [V.sub.0] + [S.sub.0] which gives the following energy eigenvalue equation from (14) as

[[[square root of ([m.sup.2.sub.0] - [E.sup.2] + 2Q[V.sub.0] (E + [M.sub.0]) + [a.sub.1])] + [square root of ([m.sup.2.sub.0] - [E.sup.2])] + [beta] (2n + 1)].sup.2] - [([beta] + Q[V.sub.1]).sup.2] = 0, (23)

with [a.sub.1] = [Q.sup.2][V.sup.2.sub.1] and [b.sub.1] = Q[V.sub.1]([beta] + Q[V.sub.1]). The corresponding wave functions are given by

[[phi].sub.1] (s) = [N.sub.1] [s.sup.[alpha]'/2] [(1 - s).sup.[beta]'/2] [P.sup.([alpha]',[beta]')] (1 - 2s), (24)

with [alpha]' = (1/[beta]) [square root of ([m.sup.2.sub.0] - [E.sup.2] + 2Q[V.sub.0] (E + [m.sub.0]) + [Q.sup.2] [V.sup.2.sub.1])], and [beta]' = (1/[beta]) [square root of ([m.sup.2.sub.0] - [E.sup.2])].

For the lower component (i = 2), we have the following energy eigenvalue equation from (14) with the potential parameter [m.sup.2] = [V.sub.0] - [S.sub.0]

[mathematical expression not reproducible], (25)

with [a.sub.2] = -4Q[m.sub.0][S.sub.0] + [Q.sup.2][V.sup.2.sub.1] - 4[Q.sup.2][S.sup.0] ([V.sub.0] - [S.sub.0]) and [b.sub.2] = -2Q[m.sub.0] - 4[Q.sup.2][S.sub.0] ([V.sub.0] - [S.sub.0]) + Q[V.sub.1] ([beta] + Q[V.sub.1]). The corresponding wave functions are written as

[[phi].sub.2] (s) = [N.sub.2][s.sup.[alpha]'/2] [(1 - s).sup.[beta]'/2] [P.sup.([alpha]',[beta]').sub.n] (1 - 2s), (26)

with

[mathematical expression not reproducible]. (27)

Before going further, we tend to give some numerical results obtained from (23) and (25) in Table 1 where one observes that the energy values for upper component are larger than the ones for lower component, and numerical values for both components decrease while quantum number n increases.

Now we can modify our results to the case where the mass is constant. Let us first write [m.sub.1] =0 which means [V.sub.0] = -[S.sub.0]. This situation corresponds to the spin symmetric case for the Dirac equation in 3 + 1 dimension [20, 21, 26]. We write the energy eigenvalue equation for the Dirac equation with the generalized Hultheen potential as

[[[square root of ([m.sup.2.sub.0] - [E.sup.2] + 2Q[V.sub.0] (E + [m.sub.0]) + [a.sub.1])] + [square root of ([m.sup.2.sub.0] - [E.sup.2])] + [beta] (2n + 1)].sup.2] - [([beta] + Q[V.sub.1]).sup.2] = 0, (28)

with [a.sub.1] = [Q.sup.2][V.sup.2.sub.1], and [b.sub.1] = Q[V.sub.1]([beta] + Q[V.sub.1]). Here, one has to choose the positive eigenvalues because in the case of the spin symmetry only the bound states with positive energy occur [26]. For the constant mass, the wave functions with normalization constant given in (21) are

[[phi].sub.1] (S) = [N.sub.1] [s.sup.[alpha]'/2] [(1 - s).sup.[beta]'/2] [P.sup.([alpha]',[beta]').sub.n] (1 - 2s), (29)

with [alpha]' = (1/[beta]) [square root of ([m.sup.2.sub.0] - [E.sup.2] + 2Q[V.sub.0] (E + [m.sub.0]) + [Q.sup.2][V.sup.2.sub.1])], and [beta]' = (1/[beta]) [square root of ([m.sup.2.sub.0] - [E.sup.2])]. The case where [m.sup.2] = 0 giving [V.sub.0] = + [S.sub.0] corresponds to the pseudospin symmetric situation for the Dirac equation [20, 21, 26], and the energy eigenvalue equation becomes

[[[square root of ([m.sup.2.sub.0] - [E.sup.2] + 2Q[V.sub.0](E + [m.sub.0]) + [a.sub.2])] + [square root of ([m.sup.2.sub.0] - [E.sub.2])] - [beta](2n + 1)].sup.2] - [([beta] + Q[V.sub.1]).sup.2] = 0, (30)

with [a.sub.2] = -4Q[m.sub.0][S.sub.0] + [Q.sup.2][V.sup.2.sub.1], and [b.sub.2] = -4Q[m.sub.0][S.sub.0] + Q[V.sub.1] ([beta] + Q[V.sub.1]). The last equation can give negative or positive eigenvalues, but one uses only negative energy eigenvalues because negative energy states can exist in the case of pseudospin symmetry [26]. The corresponding wave functions are given as

[[phi].sub.2] (s) = [N.sub.2][s.sup.[alpha]'/2] [(1 - s).sup.[beta]'/2] [P.sup.([alpha]',[beta]').sub.n] (1 - 2s), (31)

with

[mathematical expression not reproducible]. (32)

The pseudospin symmetry, as a hidden symmetry in atomic nuclei, has been suggested firstly by Arima and coworkers [29, 30]. After the pseudospin symmetry has found a place as a relativistic symmetry in literature, some special features, spin symmetry, for example, have been studied [31]. There have been many efforts about the recent progress on pseudospin and spin symmetry in different systems such as stable, exotic, deformed, and spherical nuclei. These efforts extend the subject of "hidden symmetries" in atomic nuclei to include different perspectives such as perturbative study of the pseudospin symmetry and SUSY approach to hidden symmetries combining with similarity renormalization group and studying the source of some particular states which intrude from the major shell above to the shell below forming the nuclear magic numbers 28, 50, 82, and so forth [31].

Finally, we tend to give only the eigenvalue equation for the nonrelativistic limit which can be obtained by using E - [m.sub.0] ~ E and E + [m.sub.0] - 2[m.sub.0] in (14) ([??] = c = 1)

[mathematical expression not reproducible]. (33)

The last equation gives two different results for energy eigenvalues, and one should choose the appropriate one.

4. Bound States for PT-Symmetric Forms

Let us now study the case where the potential parameter [beta] is pure imaginary which means that the potential has a complex form as follows:

V (x) = Q[V.sub.0] cos (2[beta]x) + i sin (2[beta]x)/cos (2[beta]x0) + i sin (2[beta]x) - Q, (34)

with i = [square root of (-1)]. This form of the potential in (1) is PT- symmetric because it satisfies

[[V (-*)].sup.*] = V(x), (35)

which is non-Hermitian [4]. The bound state spectra of the generalized, PT-symmetric Hultheen potential can be found from (14), and we write it explicitly as

[square root of ([m.sup.2.sub.0] - [E.sup.2] + 2Q[V.sub.0] (E + [m.sub.0]) + [a.sub.i])] + [square root of ([m.sup.2.sub.0] - [E.sup.2])] + i[beta]n' + [lambda] [square root of ([[GAMMA].sub.i])] = 0, (36)

with

n' = 2n + 1, [[GAMMA].sub.i] = [(i[beta] + Q[V.sub.i]).sup.2] + [Q.sup.2] [[([m.sub.i] - [S.sub.0]).sup.2] - [V.sup.2.sub.0]], (37)

where [lambda] = [+ or -] 1. The obtained result says that four different solutions can be possible, and we expect that one of them, at least, gives a real spectra for the PT-symmetric Hultheen potential [4]. The corresponding upper and lower components of the Dirac spinor are written with the help of (15) as

[[phi].sub.i] (s) ~ [s.sup.[alpha]"/2] [(1 - s).sup.[beta]"/2] [P.sup.([alpha]",[beta]").sub.n] (1 - 2s), (38)

where [alpha]" = -a', and [beta]" = (1/[beta]) [square root of ([E.sup.2] - [m.sup.2.sub.0])] = -[beta]'. We write the upper and lower spinor component without the normalization constant, but it can be computed in a similar way given in the above section by using a modified normalization condition written for the non-Hermitian quantum systems [25, 37, 38].

An interesting form of the potential can be obtained if all potential parameters are taken as pure imaginary; namely, [V.sub.0] [right arrow] i[V.sub.0] ([S.sub.0] [right arrow] i[S.sub.0]), [beta] [right arrow] i[beta], q [right arrow] iq, giving

V(x) = [V.sub.0] q - sin ([beta]x) - i cos ([beta]x)/[q.sup.2] - 2q sin ([beta]x) + 1 = [V.sup.*] ([pi]/2 - x), (39)

which is PT-symmetric but non-Hermitian (and also pseudoHermitian) [4, 25]. The energy spectra for this form of the potential are written as

[square root of ([m.sup.2.sub.0] - [E.sup.2] + 2Q[V.sub.0] (E + [m.sub.0]) + [a.sub.i])] + [square root of ([m.sup.2.sub.0] - [E.sup.2])] + i[beta]n' + [lambda] [square root of ([[GAMMA].sub.i])] = 0, (40)

with

[mathematical expression not reproducible]. (41)

It is worthwhile to say that one has to choose the result giving a real spectrum obtained from (40) for the above form of the generalized Hultheen potential.

5. Solutions for Specific g-Values

The value of q = +1 corresponds to the standard Hulthen potential for which the energy equation is obtained from (14), and the upper and lower components of Dirac spinor from (15). For q = -1, the generalized Hulthen potential gives

V (X) = -[V.sub.0] [e.sup.-2[beta]x]/[e.sup.-2[beta]x] + 1, (42)

which is the Woods-Saxon potential. The energy levels and upper and lower components of Dirac spinor for this form are obtained from (14) and (15), respectively.

For q = 0, we have

V(x) = -[V.sub.0][e.sup.-2[beta]], (43)

which is the exponential potential, and it is known that there is no explicit expression for the bound states for nonrelativistic, and relativistic wave equations [39-41]. Hence we have to reconsider the problem by using the new variable s = [e.sup.-2[beta]x] giving

{[d.sup.2]/d[s.sup.2] + 1/s d/ds - 1/[s.sup.2] [A'/4[[beta].sup.2] - 2B'/4[[beta].sup.2] + C'/4[[beta].sup.2] [s.sup.2]]} [[phi].sub.i] (s) = 0, (44)

with

[mathematical expression not reproducible]. (45)

We compare (44) with (A.1) in Appendix, and with the help of (A.3) we obtain the parameter set

[mathematical expression not reproducible]. (46)

Equation (A.10) gives the upper and lower component of Dirac spinor for exponential potential in (43)

[mathematical expression not reproducible]. (47)

6. Conclusions

We have analyzed the analytical solutions of the Dirac equation with scalar-vector-pseudoscalar generalized Hulthen potential in 1 + 1 dimension within the position-dependent mass formalism. We have reduced the two extended effective-mass versions of coupled equations written for the upper and lower component to a form of analytical solvable equations by relating the mass function with the potentials. We have given both energy eigenvalue equations and normalized wave functions in closed forms. We have also computed the results for the case where the mass is constant which correspond to spin and pseudospin symmetric cases in Dirac equation. We have written the results for the bound states in the nonrelativistic case. We have studied the bound state spectrum and the corresponding normalized upper and lower component of Dirac spinor for the complex, generalized Hultheen potential which are PT-symmetric, non-Hermitian forms of the potential.

Appendix

The general form of a second-order differential equation which is solved by using the parametric generalization of the Nikiforov-Uvarov method [27] is as follows:

[d.sup.2]F (s)/d[s.sup.2] + [[alpha].sub.1] - [[alpha].sub.2]s/s(1 - [[alpha].sub.3]s) dF (s)/ds - [[xi].sub.1][s.sup.2] - [[xi].sub.2]s + [[xi].sub.3]/[[s(1 - [[alpha].sub.3]s)].sup.2] F (s) = 0, (A.1)

with the quantization rule

[[alpha].sub.2]n - (2n + 1) [[alpha].sub.5] + (2n + 1) + ([square root of ([[alpha].sub.9])] + [[alpha].sub.3] [square root of ([[alpha].sub.8])]) + n(n - 1) [[alpha].sub.3] + [[alpha].sub.7] + 2[[alpha].sub.3][[alpha].sub.8] + 2[[alpha].sub.8] [square root of ([[alpha].sub.9])] = 0,

where n = 0, 1, 2, ....

The parameters [[alpha]'.sub.i]s within this approach are defined as

[mathematical expression not reproducible]. (A.3)

The corresponding wave functions are given in terms of the parameters [[alpha].sub.i] [27]

[mathematical expression not reproducible], (A.4)

where

[mathematical expression not reproducible], (A.5)

with the Jacobi polynomials [mathematical expression not reproducible] and a normalization constant N.

For the second independent solution the quantization condition is given by

[mathematical expression not reproducible], (A.6)

with the corresponding wave functions

[mathematical expression not reproducible], (A.7)

where

[mathematical expression not reproducible]. (A.8)

If a situation is appearing in the problem such as [[alpha].sub.3] = 0, then the quantization rule in (A.2) becomes

[mathematical expression not reproducible], (A.9)

with the corresponding wave functions

[mathematical expression not reproducible], (A.10)

when the limits become [mathematical expression not reproducible] with generalized Laguerre polynomials [mathematical expression not reproducible].

http://dx.doi.org/10.1155/2017/6340409

Disclosure

Present address for the author is Department of Mathematical Science, City University London, UK.

Competing Interests

The author declares that there is no conflict of interests regarding the publication of this paper.

Acknowledgments

The author thanks Professor Dr. Andreas Fring from City University London and the Department of Mathematics for hospitality. This research was partially supported through a fund provided by University of Hacettepe.

References

[1] L. Hulthen, "Uber die Eigenlosungen der Schrodingergleichung des Deuterons," Arkiv for Matematik, Astronomi och Fysik, vol. 28A, no. 5, pp. 1-12, 1942.

[2] Y. P. Varshni, "Eigenenergies and oscillator strengths for the Hulthen potential," Physical Review A, vol. 41, no. 9, pp. 4682-4689, 1990.

[3] A. Arda, R. Sever, and C. Tezcan, "Approximate analytical solutions of the effective mass Dirac equation for the generalized Hulthen potential with any K-value," Central European Journal of Physics, vol. 8, no. 5, pp. 843-849, 2010.

[4] H. Egrifes and R. Sever, "Bound states of the Dirac equation for the PT-symmetric generalized Hultheen potential by the Nikiforov-Uvarov method," Physics Letters. A, vol. 344, no. 24, pp. 117-126, 2005.

[5] C. Eckart, "The penetration of a potential barrier by electrons," Physical Review, vol. 35, no. 11, pp. 1303-1309, 1930.

[6] C. S. Lam and Y. P. Varshni, "Bound eigenstates of the exponential cosine screened coulomb potential," Physical Review A, vol. 6, no. 4, pp. 1391-1399, 1972.

[7] B. Durand and L. Durand, "Duality for heavy-quark systems," Physical Review D, vol. 23, no. 5, pp. 1092-1102, 1981.

[8] J. Lindhard and A. Winther, "Transient fields acting on heavy ions during slowing-down in magnetized materials," Nuclear Physics A, vol. 166, no. 3, pp. 413-435, 1971.

[9] P. Pyykko and J. Jokisaari, "Spectral density analysis of nuclear spin-spin coupling: I. A Hulthen potential LCAO model for JXH in hydrides XH4," Chemical Physics, vol. 10, no. 2-3, pp. 293-301, 1975.

[10] R. Dutt and Y. P. Varshni, "Extension of Fudas off-shell analysis to screened Coulomb potentials for arbitrary 1 and limiting relations," Journal of Mathematical Physics, vol. 24, no. 12, pp. 2770-2775, 1983.

[11] F. Dominguez-Adame, "Bound states of the Klein-Gordon equation with vector and scalar Hultheen-type potentials," Physics Letters A, vol. 136, no. 4-5, pp. 175-177, 1989.

[12] B. Roy and R. Roychoudhury, "The shifted 1=N expansion and the energy eigenvalues of the Hulthen potential for l [not equal to] 0," Journal of Physics A, vol. 20, pp. 3051-3055, 1987.

[13] R. L. Greene and C. Aldrich, "Variational wave functions for a screened Coulomb potential," Physical Review A, vol. 14, no. 6, pp. 2363-2366, 1976.

[14] M. Znojil, "Exact solution of the Schrodinger and Klein-Gordon equations for generalised Hulthen potentials," Journal of Physics A: Mathematical and General, vol. 14, no. 2, pp. 383-394, 1981.

[15] J. M. Cai, P. Y. Cai, and A. Inomata, "Path-integral treatment of the Hulthen potential," Physical Review A, vol. 34, no. 6, pp. 4621-4628, 1986.

[16] M. R. Setare and E. Karimi, "Algebraic approach to the Hulthen potential," International Journal of Theoretical Physics, vol. 46, no. 5, pp. 1381-1388, 2007.

[17] S. M. Ikhdair and R. Sever, "Approximate eigenvalue and eigen-function solutions for the generalized Hultheen potential with any angular momentum," Journal of Mathematical Chemistry, vol. 42, no. 3, pp. 461-471, 2007.

[18] O. Von Roos, "Position-dependent effective masses in semiconductor theory," Physical Review B, vol. 27, no. 12, pp. 7547-7552, 1983.

[19] J.-M. Levy-Leblond, "Position-dependent effective mass and Galilean invariance," Physical Review A, vol. 52, no. 3, pp. 1845-1849, 1995.

[20] S. Haouat and L. Chetouani, "Approximate solutions of Klein-Gordon and Dirac equations in the presence of the Hultheen potential," Physica Scripta, vol. 77, no. 2, Article ID 025005, 6 pages, 2008.

[21] H. Hassanabadi, B. H. Yazarloo, M. Mahmoudieh, and S. Zarrinkamar, "Dirac equation under the Deng-Fan potential and the Hulthen potential as a tensor interaction via SUSYQM," European Physical Journal Plus, vol. 128, article no. 111, 2013.

[22] A. D. Alhaidari, "Dirac equation with coupling to 1=r singular vector potentials for all angular momenta," Foundations of Physics, vol. 40, no. 8, pp. 1088-1095, 2010.

[23] A. D. Alhaidari, "Relativistic coulomb problem for Z larger than 137," International Journal of Modern Physics A, vol. 25, no. 18-19, pp. 3703-3714, 2010.

[24] A. D. Alhaidari, "Generalized spin and pseudo-spin symmetry: relativistic extension of supersymmetric quantum mechanics," Physics Letters. B, vol. 699, no. 4, pp. 309-313, 2011.

[25] L. B. Castro, A. S. de Castro, and M. Hott, "Relativistic effects of mixed vector-scalar-pseudoscalar potentials for fermions in 1 + 1 Dimensions," International Journal of Modern Physics E, vol. 16, pp. 3002-3005, 2007.

[26] K. T. Hecht and A. Adler, "Generalized seniority for favored J [not equal to] 0 pairs in mixed configurations," Nuclear Physics A, vol. 137, no. 1, pp. 129-143, 1969.

[27] D. Troltenier, C. Bahri, and J. P. Draayer, "Generalized pseudo-SU(3) model and pairing," Nuclear Physics A, vol. 586, no. 1, pp. 53-72, 1995.

[28] J. N. Ginocchio, "Relativistic symmetries in nuclei and hadrons," Physics Reports A, vol. 414, no. 4-5, pp. 165-261, 2005.

[29] A. Arima, M. Harvey, and K. Shimizu, "Pseudo LS coupling and pseudo SU3 coupling schemes," Physics Letters B, vol. 30, no. 8, pp. 517-522, 1969.

[30] K. T. Hect and A. Adler, "Generalized seniority for favored J [not equal to] 0 pairs in mixed configurations, Nucl," Nuclear Physics A, vol. 137, no. 1, pp. 129-143, 1969.

[31] H. Liang, J. Meng, and S.-G. Zhou, "Hidden pseudospin and spin symmetries and their origins in atomic nuclei," Physics Reports, vol. 570, pp. 1-84, 2015.

[32] C. Tezcan and R. Sever, "A general approach for the exact solution of the Schroodinger equation," International Journal of Theoretical Physics, vol. 48, no. 2, pp. 337-350, 2009.

[33] A. F. Nikiforov and V. B. Uvarov, Special Functions of Mathematical Physics, Birkhauser, Basel, Switzerland, 1988.

[34] C. M. Bender and S. Boettcher, "Real spectra in non-hermitian hamiltonians having PT symmetry," Physical Review Letters, vol. 80, no. 24, pp. 5243-5246, 1998.

[35] C. M. Bender, S. Boettcher, and P. N. Meisinger, "PT-symmetric quantum mechanics," Journal of Mathematical Physics, vol. 40, no. 5, pp. 2201-2229, 1999.

[36] C. M. Bender and G. V. Dunne, "Large-order perturbation theory for a non-Hermitian PT-symmetric Hamiltonian," Journal of Mathematical Physics, vol. 40, no. 10, pp. 4616-4621, 1999.

[37] M. Hamzavi and A. A. Rajabi, "Scalar-vector-pseudoscalar Cornell potential for a spin-1/2 particle under spin and pseudospin symmetries: 1 + 1 dimensions," Annals of Physics, vol. 334, pp. 316-320, 2013.

[38] S. Haouat and L. Chetouani, "Bound states of Dirac particle subjected to the pseudoscalar Hultheen potential," Journal of Physics A: Mathematical and Theoretical, vol. 40, no. 34, pp. 10541-10547, 2007.

[39] Y. Chargui, "Effective mass and pseudoscalar interaction in the dirac equation with woods-saxon potential," Few-Body Systems, vol. 57, no. 4, pp. 289-306, 2016.

[40] M. Abramowitz and I. A. Stegun, Eds., Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, Dover, New York, NY, USA, 1965.

[41] S. M. Ikhdair and R. Sever, "Bound-states of a semi-relativistic equation for the PT-symmetric generalized Hulthen potential by the Nikiforov-Uvarov method," International Journal of Modern Physics E, vol. 17, no. 6, pp. 1107-1124, 2008.

Altug Arda

Department of Physics Education, Hacettepe University, 06800 Ankara, Turkey

Correspondence should be addressed to Altug Arda; arda@hacettepe.edu.tr

Received 28 September 2016; Revised 14 December 2016; Accepted 29 December 2016; Published 24 January 2017

Academic Editor: Edward Sarkisyan-Grinbaum
TABLE 1: The variation of energy eigenvalues with different n for
[beta] = 1, [m.sub.0] = 50, [V.sub.1] = [V.sub.2] = 1.5, Q = 100,
[V.sub.0] = 1, [S.sub.0] = 2.

n   Energy values   Energy values
      for i = 1       for i = 2

0     -15.97700       -28.37410
1     -17.93500       -30.26090
2     -19.78040       -32.01920
3     -21.52680       -33.66200
4     -23.18510       -35.19950
COPYRIGHT 2017 Hindawi Limited
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2017 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Research Article
Author:Arda, Altug
Publication:Advances in High Energy Physics
Date:Jan 1, 2017
Words:5711
Previous Article:A Correlation between the Higgs Mass and Dark Matter.
Next Article:Dreibein as Prepotential for Three-Dimensional Yang-Mills Theory.

Terms of use | Privacy policy | Copyright © 2022 Farlex, Inc. | Feedback | For webmasters |