三个极限圆型Hamilton算子乘积的自伴性

本文讨论了极限圆型Hamilton算子乘积的自伴性,利用Calkin理论及奇异Hamilton系统自伴扩张的一般构造理论,给出了在极限圆型时判定三个.Hamilton算子乘积自伴的—个充要条件.     

一类乘积算子点谱的对称性及其应用

证明了一类乘积算子点谱的对称性并将其应用到Hamilton算子、反Hamilton算子上,最后举例说明了乘积算子数值域的一些性质.     

一类无穷维Hamilton算子的谱

研究了一类无穷维Hamilton算子的近似点谱及本质谱.进而通过无穷维Hamilton算子内部元素的乘积的谱对整体谱进行了刻画,最后证明了结论的正确性.     

Dirichlet空间上Bergman型Toeplitz算子的代数性质

本文讨论了Dirichlet空间上由调和函数诱导的Bergman型Toeplitz算子的基本性质和代数性质,包括此类算子的自伴性、乘积性质、交换性及可逆性,并计算了算子的谱.     

某类无穷维Hamilton算子的Moore-Penrose可逆性

设X是无穷维Hilbert空间,H表示X⊕X上的有界无穷维Hamilton算子H=(A C B-A*),其中B和C为自伴算子.本文研究了无穷维Hamilton算子H的Moore-Penrose广义逆.利用空间分解等方法,当B=0或C为Moore-Penrose可逆的情况下给出H为Moore-Penrose可逆的等价条件.此外,举例说明了结论的有效性.     

Hamilton算子的一类n次数值域的对称性

以Hamilton算子的数值域为基础,研究了一类算子的二次数值域关于实轴,虚轴的对称性.此外从α-J-自伴算子的n次数值域关于过原点直线对称出发,得到了有界Hamilton算子的一类n次数值域关于虚轴的对称性.     

m个微分算式乘积的自伴边界条件

本文假设n阶正则对称微分算式l(y)的幂算式lm(y)在L2[a,∞)中是部分分离的,首先刻画了由幂算式lm(y)生成的微分算子T(lm)的自伴边界条件.然后,在L2[a,∞)中,借助T(lm)的自伴域的这种刻画形式,研究了m个由n阶微分算式l(y)生成的微分算子Tk(l)(k=1,2,…,m;m∈z,m≥2)乘积的自伴性问题,获得了乘积算子Tm(l)…T2(l)T1(l)是自伴算子的充要条件.     

m个微分算式乘积的自伴边界条件

本文假设n阶正则对称微分算式l(y)的幂算式l~m(y)在L~2[α,∞)中是部分分离的,首先刻画了由幂算式l~m(y)生成的微分算子T(l~m)的自伴边界条件．然后,在L~2[α,∞)中,借助T(l~m)的自伴域的这种刻画形式,研究了m个由n阶微分算式l(y)生成的微分算子T_k(l)(k=1,2,……,m；m∈z,m≥2)乘积的自伴性问题,获得了乘积算子T_m(l)…T_2(l)T_1(l)是自伴算子的充要条件．     

2n阶微分算子乘积自伴的充分必要条件

给定Hilbert空间L2[a,∞)上两个由2n阶对称微分算式生成的微分算子Li(i=1,2),该文给出了乘积算子L2L1是自伴算子的一个充分必要条件．     

极限点型 Sturm-Liouville 算子乘积的自伴性

假设微分算式l(y)=-(py') qy,t∈[a,∞),满足lk(y)(k=1,2,3)均为极限点型,作者研究了由l(y)生成的两个微分算子Li(i=1,2)的乘积L2L1的自伴性问题并获得其自伴的充分必要条件．同时研究了由l(y)=-y" qy,t∈[a,∞),生成的三个微分算子Li(i=1,2,3)的乘积L3L2L1的自伴性问题．     

伪自伴量子系统的酉演化与绝热定理

经典量子系统的哈密尔顿是自伴算子.哈密尔顿算符的自伴性不仅确保了系统遵循酉演化,而且也保证了它自身具有实的能量本征值.但是,确实有一些物理系统,其哈密尔顿是非自伴的,但也具有实的能量本征值,这种具有非自伴哈密尔顿的系统就是非自伴量子系统.具有伪自伴哈密尔顿的系统是一类特殊的非自伴量子系统,其哈密尔顿相似于一个自伴算子.本文研究伪自伴量子系统的酉演化与绝热定理.首先,给出了伪自伴算子定义及其等价刻画;其次,对于伪自伴哈密尔顿系统,通过构造新内积,证明了伪自伴哈密尔顿在新内积下是自伴的,并给出了系统在新内积下为酉演化的充分必要条件.最后,建立了伪自伴量子系统的绝热演化定理及与绝热逼近定理.     

On self-adjointness of the product of two second-order differential operators

In this paper, the problem of self-adjointness of the product of two differential operators is considered. A number of results concerning self-adjointness of the productL ₂ L ₁ of two second-order self-adjoint differential operators are obtained by using the general construction theory of self-adjoint extensions of ordinary differential operators. Supported by the Royal Society and the National Natural Science Foundation of China and the Regional Science Foundation of Inner Mongolia     

Lower bound for the spectrum and the presence of pure point spectrum of a singular discrete Hamiltonian system

In this paper, criteria for limit-point (n) case of a singular discrete Hamiltonian system are established. Furthermore, the lower bound of the essential spectrum is obtained and the present of pure point spectrum is discussed for such system by using the spectral theory of self-adjoint operators in a Hilbert space.     

The multiplicative Weyl functional calculus

The Weyl calculus discussed in the author's previous papers starts with a fixed set of n noncommuting self-adjoint operators and associates an operator to a real function of n variables. The calculus is not multiplicative with respect to point-wise multiplication of functions. However, if the n self-adjoint operators generate a unitary Lie group representation, a “skew product” of functions can be defined which yields multiplicativity. This skew product depends only on the Lie group, not on the particular representation. In the case of the Heisenberg group, this skew product makes it possible to write the Schrödinger equation as an integro-differential equation on the phase plane. Strong convergence of the dynamical group, as Planck's constant goes to zero, to the classical Hamiltonian flow is proved under various conditions on the Hamiltonian.     

Some Abstract Critical Point Theorems for Self-adjoint Operator Equations and Applications

By using the index theory for linear bounded self-adjoint operators in a Hilbert space related to a fixed self-adjoint operator A with compact resolvent,the authors discuss the existence and multiplicity of solutions for(nonlinear) operator equations,and give some applications to some boundary value problems of first order Hamiltonian systems and second order Hamiltonian systems.     

半退化型离散哈密顿系统本质谱下方的特征值(英文)

本文给出了半退化型离散哈密顿系统强极限点型的判别准则,并且利用函数M(λ)的性质和Hilbert空间算子谱理论,得到了在相应的最小算子下界下方特征值存在个数的判别准则.     

无穷维Hamilton算子的辛自伴性

本文运用算子扰动理论研究了无穷维Hamilton算子的共轭算子,进而得到了无穷维Hamilton算子为辛自伴算子的若干充分条件.     

两类离散哈密顿系统极限点型的判定

利用算子的谱理论及经典的不等式,讨论两类离散哈密顿系统,得出半退化型系统为强极限点型以及Dirac型系统为极限点型的一些判别准则．     

Strong limit point criteria for a class of singular discrete linear Hamiltonian systems

This paper is concerned with the limit point case for a class of singular discrete linear Hamiltonian systems. The limit point case is divided into the strong and the weak limit point cases. Several sufficient conditions for the strong limit point case are established. In consequence, two criteria of the strong limit point case for second-order formally self-adjoint vector difference equations are obtained.     

N-body quantum scattering theory in two Hilbert spaces. III. Theory of approximations

A rigorous mathematical theory of approximations is developed for abstract nonrelativistic quantum scattering systems within the two-Hilbert-space framework. An approximate space of asymptotic states and an approximate asymptotic Hamiltonian must be specified initially. An approximate N-particle Hamiltonian is then constructed and proved to be self-adjoint. Approximate wave operators are shown to exist and, in certain interesting cases, to be asymptotically complete. Certain sequences of the approximate wave operators are proved to converge to the exact wave operators in an appropriate limit. Thus approximate scattering operators are unitary and converge to the exact scattering operator.