Abstract
In this paper, we investigate a class of nonlinear Schrödinger systems containing a nonlinear operator under Osgood-type conditions. By employing the iterative technique, the existence conditions for entire positive radial solutions of the above problem are given under the cases where components and are bounded, and are blow-up, and one of the components is bounded, while the other is blow-up. Finally, we present two examples to verify our results.
Keywords:
Osgood-type condition; Schrödinger system; monotone iterative method; nonlinear operator; radial solution MSC:
35B08; 35B09; 35J10
1. Introduction
Osgood-type condition is of great significance in the field of mathematics and has been widely applied to different equations or systems by many authors. In 1898, under the Osgood type condition
Osgood [1] presented the existence result of solutions for the following equation without the Cauchy–Lipschitz condition
where is a continuous function satisfying . Then, lots of authors began to consider applying the Osgood-type condition to other problems and gained many excellent results such as the comparison result of viscosity upper and lower solutions for fully nonlinear parabolic equations [2], the existence result of solutions for backward stochastic differential equations (BSDEs) [3], and the nonexistence result of the local solution for semilinear fractional heat Equation [4]. For more results, see [5,6,7,8,9].
The Schrödinger equation was derived from mathematical physics and closely related to several physical phenomena. In [10], Kurihura used it to model the superfluid film equation in plasma physics. In [11,12], it was used to model the phenomena of the self-channeling of a high-power ultrashort laser in matter. More examples and details of applications can be found in [13,14,15,16].
In 2017, by employing the analysis technique and weighted norm method, Sun [17] established the existence result of solutions to the following Schrödinger equation
where , , , (locally Hölder continuous), , , for .
In 2018, by introducing a growth condition and employing the iterative technique, Zhang, Wu and Cui [18] established the nonexistence and existence results of the entire blow-up solutions to the following Schrödinger equation
where , is a nonlinear operator belonging to the set .
In 2020, by employing the iterative technique, Wang et al. [19] established the existence result of the entire radial solutions for the following Schrödinger system
where , and is a nonlinear operator belonging to .
Motivated by the above work, we studied the existence of entire positive radial solutions to the following Schrödinger system
where , are continuous functions, is a nonlinear operator belonging to and are continuous functions satisfying Osgood-type conditions
and
By employing the monotone iterative method, we give the existence results of positive entire radial solutions to the Schrödinger system (1) under the cases where the components and are bounded, and are blow-up, and one of the components is bounded while the other is blow-up. The monotone iterative method plays a significant role in the study of nonlinear problem, as can be seen in [18,19,20,21,22,23,24,25,26,27,28] and the references therein. To the best of our knowledge, there is no work about the existence of the positive radial solutions of the Schrödinger system (1) under the Osgood-type conditions. In addition, our results extended the work of authors in [18,28,29,30,31,32,33].
2. Preliminaries
In this section, we give a definition, some notations, assumptions and Lemmas that are subsequently needed in the proof.
Firstly, we present the definition about the classification of solutions.
Definition 1
([34]). A solution of system (1) is called an entire bounded solution if condition (2) is established; it is called an entire blow-up solution if condition (3) is established; it is called a semifinite entire blow-up solution if condition (4) or (5) is established.
Finite case: both components μ and ν are bounded, that is
Infinite case: both components μ, ν are blow-up, that is
Semifinite Case: one of the components is bounded, while the other is blow-up, that is
or
We then present the notations as follows: , are suitably chosen,
Assume that and satisfy the following assumptions.
are increasing for every variable and for all ;
for fixed constants , there exist such that
where , , , , , ;
;
;
;
;
;
;
;
.
Lemma 1
([18]). If , let . We have
has a nonnegative increasing inverse mapping ;
If , we have
If , we have
Through the similar proof as in [19], we can obtain the following Lemma.
Lemma 2.
is a radial solution of the Schrödinger system (1) if and only if it is a solution of the following ordinary differential system
3. The Entire Positive Bounded Radial Solutions
In this section, we prove Theorems 1 and 2.
Theorem 1.
Assume that , hold, then the system (1) has an entire positive radial solution .
Proof.
Through an operation on system (6), we obtain
Obviously, the above system can be transformed into the following system
Define the sequences and on by
Using the similar arguments as in [19], we obtain the sequences and are increasing and
We then arrive at
Therefore,
By , we can obtain that and is a bijection. Clearly, the inverse function is strictly increasing on and
From the above inequalities, we obtain
and
We then arrive at
and
From the above two inequalities, we easily deduce that
and
We then arrive at
and
Now the above two inequalities can be expressed as
and
It follows from the that and are strictly increasing on and separately, we obtain
and
Since
we obtain
where and are positive constants. Moreover, from (15) and (16), we can deduce that and are bounded on for arbitrary . Therefore, the monotone sequences and are bounded and equicontinuous on . By employing the Arzela–Ascoli theorem, we obtain the subsequences of and uniformly converging towards and on . According to the arbitrariness of , we obtain that is an entire positive solution of the system (6). Thus, from Lemma 2, we obtain that is an entire positive radial solution of the system (1). □
Theorem 2.
Assuming that , , and hold, then the system (1) has an entire positive bounded radial solution such that
Proof.
On the basis of and , by Theorem 1, we see that the system (1) has an entire positive radial solution . Moreover, it follows from (19), (20) and that
and
Since and are strictly increasing on and separately, we obtain
and
Letting into the above two inequalities, we obtain
and
Then, it follows from Lemma 1, , and that
As with the above proof, we can prove that
□
4. The Entire Positive Blow-Up Radial Solutions
In this section, we prove Theorem 3.
Theorem 3.
Assume that , , and hold, then the system (1) has an entire positive blow-up radial solution .
Proof.
On the basis of , , by Theorem 1, we see that the system (1) has an entire positive radial solution . Moreover, it follows from (19) and (20) that
and
Since and are strictly increasing on and separately, we arrive at
and
When holds, we see that . Letting into the above two inequalities, we have
and
By condition , letting into the above two inequalities, we obtain
and
5. The Semifinite Entire Positive Blow-Up Radial Solutions
In this section, we prove Theorems 4 and 5.
Theorem 4.
Assuming that , , and hold, the system (1) then has a semifinite entire positive blow-up radial solution .
Proof.
Theorem 5.
Assume that , , and hold, then the system (1) has a semifinite entire positive blow-up radial solution .
6. Example
Example 1.
Consider the following Schrödinger system
Let , , then . Here , , , , then and are increasing for each variable and holds. Obviously, when , we have , , , , , ,
meaning that is established. From Theorem 1, the Schrödinger system (29) has an entire positive radial solution .
Example 2.
Consider the following Schrödinger system
Let , , then . Here, , , , , then and are increasing for each variable and holds. Obviously, when , we have , , , , , ,
meaning that is established. After a simple calculation, one has
and
meaning that is established. We then have
and
meaning that is established. From Theorem 3, the Schrödinger system (30) has an entire positive blow-up radial solution .
Example 3.
Consider the following Schrödinger system
Let , , then . Here, , , , , then and are increasing for each variable and holds. Obviously, when , we have , , , , , ,
meaning that is established. After a simple calculation, one has
and
meaning that is established. We then have
and
which mean that is established. From Theorem 3, the Schrödinger system (31) has an entire positive blow-up radial solution .
Author Contributions
G.W., Z.Z. and Z.Y. equally contributed this manuscript and approved the final version. All authors have read and agreed to the published version of this manuscript.
Funding
The work was supported by NSF of Shanxi Province, China (No. 20210302123339) and the Graduate Education and Teaching Innovation Project of Shanxi, China (No. 2021YJJG142).
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Acknowledgments
We thank the referees for their useful comments on our work that led to its improvement.
Conflicts of Interest
The authors declare that they have no competing interests.
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