ChemInform Abstract: Vibrational Spectra and Computer Simulations of 18O-Labelled NaY Zeolites.

ChemInform ◽  
2010 ◽  
Vol 28 (26) ◽  
pp. no-no
Author(s):  
E. GEIDEL ◽  
K. KRAUSE ◽  
H. FOERSTER ◽  
F. BAUER
Keyword(s):  
Computer Simulations ◽  
Vibrational Spectra ◽  
Nay Zeolites

Vibrational spectra and computer simulations of 18O-labelled NaY zeolites

1997 ◽  
Vol 93 (7) ◽  
pp. 1439-1443 ◽  
Author(s):  
Ekkehard Geidel ◽  
a*† Knut Krause ◽  
Horst Förster ◽  
Frank Bauer
Keyword(s):  
Computer Simulations ◽  
Vibrational Spectra ◽  
Nay Zeolites

Vibrational Spectra for Hydrogenated Amorphous Semiconductors

1989 ◽  
Vol 166 ◽  
Author(s):  
W. A. Kamitakahara ◽  
R. Biswas ◽  
A. M. Bouchard ◽  
F. Gompf ◽  
J. B. Suck
Keyword(s):  
Neutron Scattering ◽  
Computer Simulations ◽  
Vibrational Spectra ◽  
Amorphous Semiconductor ◽  
Amorphous Semiconductors ◽  
Semiconductor Materials ◽  
Vibration Spectra ◽  
Hydrogenated Amorphous

ABSTRACTHydrogen vibration spectra have been measured by neutron scattering for several amorphous semiconductor materials, including a-Ge:H and a-SiC:H samples containing about 10 at. % H. The data for a-Ge:H are compared in detail with the results of realistic computer simulations.

scholarly journals Modelling of spectroscopic and structural properties using molecular dynamics

2014 ◽  
Author(s):  
Francesco Muniz-Miranda
Keyword(s):  
Molecular Dynamics ◽  
Structural Properties ◽  
Intermolecular Interactions ◽  
Computer Simulations ◽  
Vibrational Spectra ◽  
Blue Shift ◽  
Structural Features ◽  
Vibrational Frequencies ◽  
Molecular Vibrations ◽  
Confined Water

The work described here was carried out at the European Lab. for Non-Linear Spectroscopy (LENS) to achieve a better understanding of molecular vibrations employing computer simulations. H-bonds are the main intermolecular interactions affecting vibrational spectra and here it’s shown how they usually induce a (red or blue) shift on the vibrational frequencies of the groups engaged in them, and how this shift nicely correlates with structural properties. H-bonds can be present also in a bifurcated arrangement. In systems such as confined water, this bifurcated configuration has long lifetimes, allowing it to be studied by both spectroscopic and computational means. The computational protocols implemented and adopted here allow for a direct comparison between structural features and vibrational spectra.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Multislice calculations for quasi-periodic and non-periodic objects

1990 ◽  
Vol 48 (4) ◽  
pp. 138-139
Author(s):  
R. Herrera ◽  
A. Gómez
Keyword(s):  
Electron Diffraction ◽  
Computer Simulations ◽  
Periodic Table ◽  
Amorphous Materials ◽  
Space Group ◽  
Essential Step ◽  
Shape Effects ◽  
Atomic Scattering ◽  
Diffraction Patterns ◽  
Periodic Continuation

Computer simulations of electron diffraction patterns and images are an essential step in the process of structure and/or defect elucidation. So far most programs are designed to deal specifically with crystals, requiring frequently the space group as imput parameter. In such programs the deviations from perfect periodicity are dealt with by means of “periodic continuation”.However, for many applications involving amorphous materials, quasiperiodic materials or simply crystals with defects (including finite shape effects) it is convenient to have an algorithm capable of handling non-periodicity. Our program “HeGo” is an implementation of the well known multislice equations in which no periodicity assumption is made whatsoever. The salient features of our implementation are: 1) We made Gaussian fits to the atomic scattering factors for electrons covering the whole periodic table and the ranges [0-2]Å−1 and [2-6]Å−1.

Computer simulations for the TEM bend contour technique

1996 ◽  
Vol 54 ◽  
pp. 134-135
Author(s):  
Vladimir Yu. Kolosov ◽  
Anders R. Thölén
Keyword(s):  
Computer Simulations ◽  
Real Space ◽  
Advantages And Disadvantages ◽  
Short Overview ◽  
Diffraction Contrast ◽  
Beam Method ◽  
Convergent Beam ◽  
Contour Technique

In this paper we give a short overview of two TEM applications utilizing the extinction bend contour technique (BC) giving the advantages and disadvantages; especially we consider two areas in which the BC technique remains unique. Special attention is given to an approach including computer simulations of TEM micrographs.BC patterns are often observed in TEM studies but are rarely exploited in a serious way. However, this type of diffraction contrast was one of the first to be used for analysis of imperfections in crystalline foils, but since then only some groups have utilized the BC technique. The most extensive studies were performed by Steeds, Eades and colleagues. They were the first to demonstrate the unique possibilities of the BC method and named it real space crystallography, which developed later into the somewhat similar but more powerful convergent beam method. Maybe, due to the difficulties in analysis, BCs have seldom been used in TEM, and then mainly to visualize different imperfections and transformations.

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