- About this Journal ·
- Abstracting and Indexing ·
- Aims and Scope ·
- Annual Issues ·
- Article Processing Charges ·
- Author Guidelines ·
- Bibliographic Information ·
- Citations to this Journal ·
- Contact Information ·
- Editorial Board ·
- Editorial Workflow ·
- Free eTOC Alerts ·
- Publication Ethics ·
- Recently Accepted Articles ·
- Reviewers Acknowledgment ·
- Submit a Manuscript ·
- Subscription Information ·
- Table of Contents

Abstract and Applied Analysis

VolumeÂ 2012Â (2012), Article IDÂ 687321, 12 pages

http://dx.doi.org/10.1155/2012/687321

## A Note on Nonlocal Boundary Value Problems for Hyperbolic SchrĂ¶dinger Equations

Department of Mathematics, Duzce University, Konuralp, 81620 Duzce, Turkey

Received 12 February 2012; Accepted 8 April 2012

Academic Editor: AllaberenÂ Ashyralyev

Copyright Â© 2012 Yildirim Ozdemir and Mehmet Kucukunal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### Abstract

The nonlocal boundary value problem , , , , , , for hyperbolic SchrĂ¶dinger equations in a Hilbert space with the self-adjoint positive definite operator is considered. The stability estimates for the solution of this problem are established. In applications, the stability estimates for solutions of the mixed-type boundary value problems for hyperbolic SchrĂ¶dinger equations are obtained.

#### 1. Introduction

Methods of solutions of nonlocal boundary value problems for partial differential equations and partial differential equations of mixed type have been studied extensively by many researches (see, e.g., [1â€“12] and the references given therein).

In the present paper, the nonlocal boundary value problem for differential equations of hyperbolic SchrĂ¶dinger type in a Hilbert space with self-adjoint positive definite operator is considered.

It is known that various nonlocal boundary value problems for the hyperbolic SchrĂ¶dinger equations can be reduced to problem (1.1).

A function is called a solution of the problem (1.1) if the following conditions are satisfied.(i) is twice continuously differentiable on the interval (0,1] and continuously differentiable on the segment . The derivatives at the endpoints of the segment are understood as the appropriate unilateral derivatives.(ii)The element belongs to for all , and the function is continuous on the segment .(iii) satisfies the equations and nonlocal boundary condition (1.1).

In the present paper, the stability estimates for the solution of the problem (1.1) for the hyperbolic SchrĂ¶dinger equation are established. In applications, the stability estimates for the solutions of the mixed-type boundary value problems for hyperbolic SchrĂ¶dinger equations are obtained.

Finally note that hyperbolic SchrĂ¶dinger equations play important role in physics and engineering (see, e.g., [13â€“16] and the references given therein).

Furthermore, the investigation of the numerical solution of initial value problems and SchrĂ¶dinger equations is the subject of extensive research activity during the last decade (indicatively [17â€“25] and the references given therein).

#### 2. The Main Theorem

Let be a Hilbert space, and let be a positive definite self-adjoint operator with , where . Throughout this paper, is a strongly continuous cosine operator function defined by

Then, from the definition of the sine operator function

it follows that

For the theory of cosine operator function, we refer to Fattorini [26] and Piskarev and Shaw [27].

We begin with two lemmas that will be needed as follows.

Lemma 2.1. *The following estimates hold:
*

Lemma 2.2. *Let
**
Then, the operator
**
has an inverse
**
and the estimate
**
holds, where does not depend on and .*

*Proof. *Actually, the proof of estimate (2.8) is based on the following estimate:
Using the definitions of cosine and sine operator functions, , (positivity), and (self-adjointness property), we obtain
Since
we have that
Hence, Lemma 2.2 is proved.

Now, we will obtain the formula for solution of problem (1.1). It is known that for smooth data of initial value problems

there are unique solutions of problems (2.13), and following formulas hold: Using (2.14), (2.15), and (1.1), we can write

Now, using the nonlocal boundary condition

we obtain the operator equation:

Since the operator

has an inverse

for the solution of the operator equation (2.18), we have the formula

Thus, for the solution of the nonlocal boundary value problem (1.1) we obtain (2.15), (2.16), and (2.21).

Theorem 2.3. *Suppose that , and . Let be continuously differentiable on and let be twice continuously differentiable on functions. Then, there is a unique solution of the problem (1.1) and the following stability inequalities
**
hold, where is independent of , and .*

Note that there are three inequalities in Theorem 2.3 on the stability of solution, stability of first derivative of solution and stability of second derivative of solution. That means the solution of problem (1.1) and its first and second derivatives are continuously dependent on and .

*Proof. * First, estimate (2.22) will be obtained. Using formula (2.21) and integration by parts, we obtain
Using estimates (2.4), and (2.8), we get
Applying to the formula (2.25) and using estimates (2.4) and (2.8), we can write
Using formulas (2.15) and (2.16) and integration by parts, we obtain
Using estimates (2.4) we get
Then, from estimates (2.26), (2.27), and (2.29) it follows (2.22).

Second, (2.23) will be obtained. Applying to the formula (2.25) and using estimates (2.4),and (2.8), we obtain
Applying to the formula (2.25) and using estimates (2.4), (2.8), we get
Applying to the formulas (2.28), and using estimates (2.4) we can write
Combining estimates (2.30), (2.31),and (2.32), we get estimate (2.23).

Third, estimate (2.24) will be obtained. Using formula (2.25) and integration by parts, we obtain
Applying to formula (2.33) and using estimates (2.4) and (2.8), we get
Applying to formula (2.33) and using estimates (2.4), and (2.8) we can write
Using formulas (2.28), and integration by parts, we obtain
Applying to the formulas (2.36), and using estimates (2.4), we get
From (2.34) and (2.35) and estimates (2.37) it follows (2.24). This completes the proof of Theorem 2.3.

*Remark 2.4. *We can obtain the same stability results for the solution of the following multipoint nonlocal boundary value problem:
for differential equations of mixed type in a Hilbert space with self-adjoint positive definite operator .

#### 3. Applications

Initially, the mixed problem for the hyperbolic SchrĂ¶dinger equation is considered, where . The problem (3.1) has a unique smooth solution for smooth , , , and functions.

We introduce the Hilbert space of all the square integrable functions defined on and Hilbert spaces and equipped with norms

respectively. This allows us to reduce the mixed problem (3.1) to the nonlocal boundary value problem (1.1) in Hilbert space with a self-adjoint positive definite operator defined by problem (3.1).

Theorem 3.1. *The solutions of the nonlocal boundary value problem (3.1) satisfy the following stability estimates:
**
where does not depend on not only and but also .*

The proof of Theorem 3.1 is based on the abstract Theorem 2.3 and symmetry properties of the space operator defined by problem (3.1).

Next, we consider the mixed nonlocal boundary value problem for the multidimensional hyperbolic SchrĂ¶dinger equation: where is the unit open cube in the -dimensional Euclidean space :

with boundary and . Here, , and are given smooth functions in and .

We introduce the Hilbert space of all square integrable functions defined on , equipped with the norm

and Hilbert spaces and defined on , equipped with norms

respectively. The problem (3.4) has a unique smooth solution for smooth , and functions. This allows us to reduce the mixed problem (3.4) to the nonlocal boundary value problem (1.1) in Hilbert space with a self-adjoint positive definite operator defined by problem (3.4).

Theorem 3.2. *The following stability inequalities for solutions of the nonlocal boundary value problem (3.4)
**
hold. Here, is independent of , and .*

The proof of Theorem 3.2 is based on the abstract Theorem 2.3, symmetry properties of the space operator defined by problem (3.4), and the following theorem on the coercivity inequality for the solution of the elliptic differential problem in in Sobolevskii [28].

Theorem 3.3. *For the solutions of the elliptic differential problem
**
the following coercivity inequality holds:
*

#### Acknowledgment

The authors would like to thank Professor Allaberen Ashyralyev (Fatih University, Turkey) for his helpful suggestions to the improvement of this paper.

#### References

- M. S. Salakhitdinov,
*Equations of Mixed-Composite Type*, FAN, Tashkent, Uzbekistan, 1974. - T. D. Djuraev,
*Boundary Value Problems for Equations of Mixed and Mixed-Composite Types*, FAN, Tashkent, Uzbekistan, 1979. - M. G. Karatopraklieva, â€śA nonlocal boundary value problem for an equation of mixed type,â€ť
*Differensial’nye Uravneniya*, vol. 27, no. 1, p. 68, 1991 (Russian). View at Zentralblatt MATH - D. Bazarov and H. Soltanov,
*Some Local and Nonlocal Boundary Value Problems for Equations of Mixed and Mixed-Composite Types*, Ylym, Ashgabat, Turkmenistan, 1995. - S. N. Glazatov, â€śNonlocal boundary value problems for linear and nonlinear equations of variable type,â€ť
*Sobolev Institute of Mathematics SB RAS*, no. 46, p. 26, 1998. - A. Ashyralyev and N. Aggez, â€śA note on the difference schemes of the nonlocal boundary value problems for hyperbolic equations,â€ť
*Numerical Functional*, vol. 25, no. 5-6, pp. 439â€“462, 2004. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - A. Ashyralyev and Y. Ozdemir, â€śOn nonlocal boundary value problems for hyperbolic-parabolic equations,â€ť
*Taiwanese Journal of Mathematics*, vol. 11, no. 4, pp. 1075â€“1089, 2007. View at Zentralblatt MATH - A. Ashyralyev and O. Gercek, â€śNonlocal boundary value problems for elliptic-parabolic differential and difference equations,â€ť
*Discrete Dynamics in Nature and Society*, vol. 2008, Article ID 904824, 16 pages, 2008. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - A. Ashyralyev and A. Sirma, â€śNonlocal boundary value problems for the Schrödinger equation,â€ť
*Computers & Mathematics with Applications*, vol. 55, no. 3, pp. 392â€“407, 2008. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - A. Ashyralyev and O. Yildirim, â€śOn multipoint nonlocal boundary value problems for hyperbolic differential and difference equations,â€ť
*Taiwanese Journal of Mathematics*, vol. 14, no. 1, pp. 165â€“194, 2010. View at Zentralblatt MATH - A. Ashyralyev and B. Hicdurmaz, â€śA note on the fractional Schrödinger differential equations,â€ť
*Kybernetes*, vol. 40, no. 5-6, pp. 736â€“750, 2011. View at Publisher Â· View at Google Scholar - A. Ashyralyev and F. Ozger, â€śThe hyperbolic-elliptic equation with the nonlocal condition,â€ť
*AIP Conference Proceedings*, vol. 1389, pp. 581â€“584, 2011. View at Publisher Â· View at Google Scholar - Z. Zhao and X. Yu, â€śHyperbolic Schrödinger equation,â€ť
*Advances in Applied Clifford Algebras*, vol. 14, no. 2, pp. 207â€“213, 2004. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - A. A. Oblomkov and A. V. Penskoi, â€śLaplace transformations and spectral theory of two-dimensional semidiscrete and discrete hyperbolic Schrödinger operators,â€ť
*International Mathematics Research Notices*, no. 18, pp. 1089â€“1126, 2005. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - A. Avila and R. Krikorian, â€śReducibility or nonuniform hyperbolicity for quasiperiodic Schrödinger cocycles,â€ť
*Annals of Mathematics*, vol. 164, no. 3, pp. 911â€“940, 2006. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - M. Kozlowski and J. M. Kozlowska, â€śDevelopment on the Schrodinger equation for attosecond laser pulse interaction with planck gas,â€ť
*Laser in Engineering*, vol. 20, no. 3-4, pp. 157â€“166, 2010. - K. Tselios and T. E. Simos, â€śRunge-Kutta methods with minimal dispersion and dissipation for problems arising from computational acoustics,â€ť
*Journal of Computational and Applied Mathematics*, vol. 175, no. 1, pp. 173â€“181, 2005. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - D. P. Sakas and T. E. Simos, â€śMultiderivative methods of eighth algebraic order with minimal phase-lag for the numerical solution of the radial Schrödinger equation,â€ť
*Journal of Computational and Applied Mathematics*, vol. 175, no. 1, pp. 161â€“172, 2005. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - G. Psihoyios and T. E. Simos, â€śA fourth algebraic order trigonometrically fitted predictor-corrector scheme for IVPs with oscillating solutions,â€ť
*Journal of Computational and Applied Mathematics*, vol. 175, no. 1, pp. 137â€“147, 2005. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - Z. A. Anastassi and T. E. Simos, â€śAn optimized Runge-Kutta method for the solution of orbital problems,â€ť
*Journal of Computational and Applied Mathematics*, vol. 175, no. 1, pp. 1â€“9, 2005. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - T. E. Simos, â€śClosed Newton-Cotes trigonometrically-fitted formulae of high order for long-time integration of orbital problems,â€ť
*Applied Mathematics Letters*, vol. 22, no. 10, pp. 1616â€“1621, 2009. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - S. Stavroyiannis and T. E. Simos, â€śOptimization as a function of the phase-lag order of nonlinear explicit two-step $P$-stable method for linear periodic IVPs,â€ť
*Applied Numerical Mathematics*, vol. 59, no. 10, pp. 2467â€“2474, 2009. View at Publisher Â· View at Google Scholar - T. E. Simos, â€śExponentially and trigonometrically fitted methods for the solution of the Schrödinger equation,â€ť
*Acta Applicandae Mathematicae*, vol. 110, no. 3, pp. 1331â€“1352, 2010. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - M. E. Koksal, â€śRecent developments on operator-difference schemes for solving nonlocal BVPs for the wave equation,â€ť
*Discrete Dynamics in Nature and Society*, vol. 2011, Article ID 210261, 14 pages, 2011. View at Publisher Â· View at Google Scholar - A. Ashyralyev and M. E. Koksal, â€śOn the numerical solution of hyperbolic PDEs with variable space operator,â€ť
*Numerical Methods for Partial Differential Equations*, vol. 25, no. 5, pp. 1086â€“1099, 2009. View at Publisher Â· View at Google Scholar Â· View at Zentralblatt MATH - H. O. Fattorini,
*Second Order Linear Differential Equations in Banach Spaces*, vol. 108 of*North-Holland Mathematics Studies*, North-Holland, Amsterdam, The Netherlands, 1985. - S. Piskarev and S.-Y. Shaw, â€śOn certain operator families related to cosine operator functions,â€ť
*Taiwanese Journal of Mathematics*, vol. 1, no. 4, pp. 527â€“546, 1997. View at Zentralblatt MATH - P. E. Sobolevskii,
*Difference Methods for the Approximate Solution of Differential Equations*, Izdat, Voronezh Gosud University, Voronezh, Russia, 1975.