On the determination of equilibrium geometries and potential functions of simple polyatomic molecules from electron diffraction

1990 ◽  
Vol 1 (2-3) ◽  
pp. 217-225 ◽  
Author(s):  
A. A. Ischenko ◽  
Yu. I. Tarasov ◽  
V. P. Spiridonov
Author(s):  
E.S. Bekhtereva ◽  
◽  
O.V. Gromova ◽  
P.A. Glushkov ◽  
A.S. Belova ◽  
...  

A method of precise eigenvalues determination is developed on the basis of high order perturbation theory and applied to di-atomic molecule, as an example. The proposed method makes it possible not only to obtain energy values, but also to estimate a prediction accuracy and limits of its applicability for a specific implemented model. Numerical calculations are performed with the use of the extended Morse oscillator functions. The sixth power of the Morse coordinate is included into the potential function expansion. Analysis of possibility to make calculation in the model of the "truncated" matrix of the Hamiltonian is performed. The comparative possibilities of the method are analyzed with respect to other approaches of the potential functions determination for polyatomic molecules.


Author(s):  
L. -M. Peng ◽  
M. J. Whelan

In recent years there has been a trend in the structure determination of reconstructed surfaces to use high energy electron diffraction techniques, and to employ a kinematic approximation in analyzing the intensities of surface superlattice reflections. Experimentally this is motivated by the great success of the determination of the dimer adatom stacking fault (DAS) structure of the Si(111) 7 × 7 reconstructed surface.While in the case of transmission electron diffraction (TED) the validity of the kinematic approximation has been examined by using multislice calculations for Si and certain incident beam directions, far less has been done in the reflection high energy electron diffraction (RHEED) case. In this paper we aim to provide a thorough Bloch wave analysis of the various diffraction processes involved, and to set criteria on the validity for the kinematic analysis of the intensities of the surface superlattice reflections.The validity of the kinematic analysis, being common to both the TED and RHEED case, relies primarily on two underlying observations, namely (l)the surface superlattice scattering in the selvedge is kinematically dominating, and (2)the superlattice diffracted beams are uncoupled from the fundamental diffracted beams within the bulk.


2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Yongxia Guo ◽  
Guangsheng Wei ◽  
Ruoxia Yao

Abstract In this paper, we are concerned with the inverse spectral problems for differential pencils defined on $[0,\pi ]$ [ 0 , π ] with an interior discontinuity. We prove that two potential functions are determined uniquely by one spectrum and a set of values of eigenfunctions at some interior point $b\in (0,\pi )$ b ∈ ( 0 , π ) in the situation of $b=\pi /2$ b = π / 2 and $b\neq \pi /2$ b ≠ π / 2 . For the latter, we need the knowledge of a part of the second spectrum.


Analysis ◽  
2020 ◽  
Vol 40 (1) ◽  
pp. 39-45
Author(s):  
Yasser Khalili ◽  
Dumitru Baleanu

AbstractIn the present work, the interior spectral data is used to investigate the inverse problem for a diffusion operator with an impulse on the half line. We show that the potential functions {q_{0}(x)} and {q_{1}(x)} can be uniquely established by taking a set of values of the eigenfunctions at some internal point and one spectrum.


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