In mathematical physics, a Pöschl–Teller potential , named after the physicists Herta Pöschl[ 1] (credited as G. Pöschl) and Edward Teller , is a special class of potentials for which the one-dimensional Schrödinger equation can be solved in terms of special functions .
Definition
In its symmetric form is explicitly given by[ 2]
Symmetric Pöschl–Teller potential:
− − -->
λ λ -->
(
λ λ -->
+
1
)
2
sech
2
-->
(
x
)
{\displaystyle -{\frac {\lambda (\lambda +1)}{2}}\operatorname {sech} ^{2}(x)}
. It shows the eigenvalues for μ=1, 2, 3, 4, 5, 6.
V
(
x
)
=
− − -->
λ λ -->
(
λ λ -->
+
1
)
2
s
e
c
h
2
(
x
)
{\displaystyle V(x)=-{\frac {\lambda (\lambda +1)}{2}}\mathrm {sech} ^{2}(x)}
and the solutions of the time-independent Schrödinger equation
− − -->
1
2
ψ ψ -->
″
(
x
)
+
V
(
x
)
ψ ψ -->
(
x
)
=
E
ψ ψ -->
(
x
)
{\displaystyle -{\frac {1}{2}}\psi ''(x)+V(x)\psi (x)=E\psi (x)}
with this potential can be found by virtue of the substitution
u
=
t
a
n
h
(
x
)
{\displaystyle u=\mathrm {tanh(x)} }
, which yields
[
(
1
− − -->
u
2
)
ψ ψ -->
′
(
u
)
]
′
+
λ λ -->
(
λ λ -->
+
1
)
ψ ψ -->
(
u
)
+
2
E
1
− − -->
u
2
ψ ψ -->
(
u
)
=
0
{\displaystyle \left[(1-u^{2})\psi '(u)\right]'+\lambda (\lambda +1)\psi (u)+{\frac {2E}{1-u^{2}}}\psi (u)=0}
.
Thus the solutions
ψ ψ -->
(
u
)
{\displaystyle \psi (u)}
are just the Legendre functions
P
λ λ -->
μ μ -->
(
tanh
-->
(
x
)
)
{\displaystyle P_{\lambda }^{\mu }(\tanh(x))}
with
E
=
− − -->
μ μ -->
2
2
{\displaystyle E=-{\frac {\mu ^{2}}{2}}}
, and
λ λ -->
=
1
,
2
,
3
⋯ ⋯ -->
{\displaystyle \lambda =1,2,3\cdots }
,
μ μ -->
=
1
,
2
,
⋯ ⋯ -->
,
λ λ -->
− − -->
1
,
λ λ -->
{\displaystyle \mu =1,2,\cdots ,\lambda -1,\lambda }
. Moreover, eigenvalues and scattering data can be explicitly computed.[ 3] In the special case of integer
λ λ -->
{\displaystyle \lambda }
, the potential is reflectionless and such potentials also arise as the N-soliton solutions of the Korteweg–De Vries equation .[ 4]
The more general form of the potential is given by[ 2]
V
(
x
)
=
− − -->
λ λ -->
(
λ λ -->
+
1
)
2
s
e
c
h
2
(
x
)
− − -->
ν ν -->
(
ν ν -->
+
1
)
2
c
s
c
h
2
(
x
)
.
{\displaystyle V(x)=-{\frac {\lambda (\lambda +1)}{2}}\mathrm {sech} ^{2}(x)-{\frac {\nu (\nu +1)}{2}}\mathrm {csch} ^{2}(x).}
Rosen–Morse potential
A related potential is given by introducing an additional term:[ 5]
V
(
x
)
=
− − -->
λ λ -->
(
λ λ -->
+
1
)
2
s
e
c
h
2
(
x
)
− − -->
g
tanh
-->
x
.
{\displaystyle V(x)=-{\frac {\lambda (\lambda +1)}{2}}\mathrm {sech} ^{2}(x)-g\tanh x.}
See also
References list
^ " "Edward Teller Biographical Memoir." by Stephen B. Libby and Andrew M. Sessler, 2009 (published in Edward Teller Centennial Symposium: modern physics and the scientific legacy of Edward Teller , World Scientific, 2010" (PDF) . Archived from the original (PDF) on 2017-01-18. Retrieved 2011-11-29 .
^ a b Pöschl, G.; Teller, E. (1933). "Bemerkungen zur Quantenmechanik des anharmonischen Oszillators". Zeitschrift für Physik . 83 (3–4): 143–151. Bibcode :1933ZPhy...83..143P . doi :10.1007/BF01331132 . S2CID 124830271 .
^ Siegfried Flügge Practical Quantum Mechanics (Springer, 1998)
^ Lekner, John (2007). "Reflectionless eigenstates of the sech2 potential". American Journal of Physics . 875 (12): 1151–1157. Bibcode :2007AmJPh..75.1151L . doi :10.1119/1.2787015 .
^ Barut, A. O.; Inomata, A.; Wilson, R. (1987). "Algebraic treatment of second Poschl-Teller, Morse-Rosen and Eckart equations" . Journal of Physics A: Mathematical and General . 20 (13): 4083. Bibcode :1987JPhA...20.4083B . doi :10.1088/0305-4470/20/13/017 . ISSN 0305-4470 .
External links