Temperature-Dependent Spectrum of an Antiferroelectric Linear Chain Model

1962 ◽  
Vol 128 (2) ◽  
pp. 638-645 ◽  
Author(s):  
B. D. Silverman
Keyword(s):  
Linear Chain ◽  
Chain Model ◽  
Temperature Dependent

Linear-chain-model interpretation of resonant Raman scattering inGenSimmicrostructures

1996 ◽  
Vol 53 (23) ◽  
pp. 15871-15877 ◽  
Author(s):  
M. A. Araújo Silva ◽  
E. Ribeiro ◽  
P. A. Schulz ◽  
F. Cerdeira ◽  
J. C. Bean
Keyword(s):  
Raman Scattering ◽  
Linear Chain ◽  
Chain Model ◽  
Model Interpretation ◽  
Resonant Raman ◽  
Resonant Raman Scattering

A cyanide-bridged FeIII–MnII heterobimetallic one-dimensional coordination polymer: synthesis, crystal structure, experimental and theoretical magnetism investigation

2019 ◽  
Vol 75 (11) ◽  
pp. 1475-1481 ◽  
Author(s):  
Wenlong Lan ◽  
Zhen Zhou ◽  
Jie Li ◽  
Yong Dou ◽  
Xiaoyun Hao ◽  
...  
Keyword(s):  
Coordination Polymer ◽  
Single Crystal ◽  
Density Functional ◽  
Linear Chain ◽  
Coupling Constants ◽  
Antiferromagnetic Coupling ◽  
Chain Model ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray

A new cyanide-bridged FeIII–MnII heterobimetallic coordination polymer (CP), namely catena-poly[[[N,N′-(1,2-phenylene)bis(pyridine-2-carboxamidato)-κ4 N,N′,N′′,N′′′]iron(III)]-μ-cyanido-κ2 C:N-[bis(4,4′-bipyridine-κN)bis(methanol-κO)manganese(II)]-μ-cyanido-κ2 N:C], {[FeMn(C18H12N4O2)(CN)2(C10H8N2)2(CH3OH)2]ClO4} n , (1), was prepared by the self-assembly of the trans-dicyanidoiron(III)-containing building block [Fe(bpb)(CN)2]− [bpb2− = N,N′-(1,2-phenylene)bis(pyridine-2-carboxamidate)], [Mn(ClO4)2]·6H2O and 4,4′-bipyridine, and was structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography and powder X-ray diffraction (PXRD). Single-crystal X-ray diffraction analysis shows that CP 1 possesses a cationic linear chain structure consisting of alternating cyanide-bridged Fe–Mn units, with free perchlorate as the charge-balancing anion, which can be further extended into a two-dimensional supramolecular sheet structure via inter-chain π–π interactions between the 4,4′-bipyridine ligands. Within the chain, each MnII ion is six-coordinated by an N6 unit and is involved in a slightly distorted octahedral coordination geometry. Investigation of the magnetic properties of 1 reveals an antiferromagnetic coupling between the cyanide-bridged FeIII and MnII ions. A best fit of the magnetic susceptibility based on the one-dimensional alternating chain model leads to the magnetic coupling constants J 1 = −1.35 and J 2 = −1.05 cm−1, and the antiferromagnetic coupling was further confirmed by spin Hamiltonian-based density functional theoretical (DFT) calculations.

Interface Effects on the Raman Spectra of Si/3C-SiC Superlattices

2000 ◽  
Vol 640 ◽  
Author(s):  
E. F. Bezerra ◽  
A. G. Souza Filho ◽  
J. Mendes Filho ◽  
V. Lemos ◽  
V. N. Freire ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Theoretical Calculations ◽  
Linear Chain ◽  
Dispersion Relations ◽  
Chain Model ◽  
Virtual Crystal Approximation ◽  
Smooth Interface ◽  
Bond Polarizability ◽  
Interface Effects

ABSTRACTTheoretical calculations are performed on the role of smooth interfaces in the Raman spectra of Si/3C-SiC superlattices. The dispersion relations were obtained using a linear chain model with the alloyed interface δ-(3C-SiC)0.5(Si)0.5 described in the virtual crystal approximation. A modified bond-polarizability model was used to calculate the Raman spectra. The main results are the enhancement of the Raman spectra and the appearance of new peaks in between those related to the Si quasi confined and the 3C-SiC-confined modes with increasing number δ?of interfacial monolayers (3C-SiC)0.5(Si)0.5. Some of the smooth interface related Raman peaks have intensity comparable with those of an abrupt Si/3C-SiC superlattice.

Complex force-constant dependence of elastic constants

1990 ◽  
Vol 68 (1) ◽  
pp. 14-22 ◽  
Author(s):  
H. A. Rafizadeh
Keyword(s):  
Elastic Constant ◽  
Force Constant ◽  
Elastic Constants ◽  
Theoretical Calculations ◽  
Linear Chain ◽  
Chain Model ◽  
Crystalline Solids ◽  
Young’S Moduli ◽  
Complex Functions ◽  
Two Parameter

Expressions for the inner and bare components of the elastic constants of crystalline solids are derived. The inner elastic constants are complex functions of the force constants and vanish only for centrosymmetric solids. Using a linear-chain model, the force-constant dependence of inner, bare, and total elastic constants is studied. The linear-chain model is also utilized in derivation of composition-dependent elastic constant equations. Single-parameter and two-parameter theoretical calculations are compared with the experimental composition-dependent Young's moduli of a number of metal–metalloid glasses.

Lattice relaxation around impurity pairs in alkali halides

1976 ◽  
Vol 54 (19) ◽  
pp. 2010-2017
Author(s):  
T. L. Templeton ◽  
B. P. Clayman
Keyword(s):  
Nearest Neighbor ◽  
Molecular Model ◽  
Linear Chain ◽  
Alkali Halides ◽  
Lattice Relaxation ◽  
Resonant Absorption ◽  
Force Constants ◽  
Chain Model ◽  
Absorption Frequencies ◽  
Good Agreement

The rigid ion model is applied to the calculation of the relaxation of the lattice around single impurities and pairs of impurities in alkali halide host-defect systems. The calculated relaxation of nearest neighbors is typically a few percent of the host crystal lattice constant. Relaxation falls off with increasing distance from the defects. Nearest neighbor force constants derived from this calculation are, in some cases, in good agreement with those obtained by fitting the resonant absorption frequencies of the vibrational modes of these impurity centres to a molecular model. In other cases the extreme anisotropy of the relaxed force constants is seen to prevent the application of a simple molecular model. The calculated force constants, when used in a linear chain model, give good qualitative agreement with experiment.

scholarly journals Spontaneous dimensional reduction and novel ground state degeneracy in a simple chain model

2021 ◽  
Author(s):  
Tatjana Skrbic ◽  
Trinh Xuan Hoang ◽  
Achille Giacometti ◽  
Amos Maritan ◽  
Jayanth R. Banavar
Keyword(s):  
Ground State ◽  
Dimensional Reduction ◽  
Layer Structure ◽  
Linear Chain ◽  
Ground States ◽  
Random Coil ◽  
Chain Molecule ◽  
Temperature Phase ◽  
Chain Model ◽  
Ground State Structures

Chain molecules play a key role in the polymer field and in living cells.Our focus is on a new homopolymer model of a linear chain molecule subject to an attractive self-interaction promoting compactness. We analyze the model using simple analytic arguments complemented by extensive computer simulations. We find several striking results: there is a first order transition from a high temperature random coil phase to a highly unusual low temperature phase; the modular ground states exhibit significant degeneracy; the ground state structures exhibit spontaneous dimensional reduction and have a two-layer structure; and the ground states are assembled from secondary motifs of helices and strands connected by tight loops. We discuss the similarities and notable differences between the ground state structures (we call these PoSSuM - Planar Structures with Secondary Motifs) in the novel phase and protein native state structures.

Sign in / Sign up

Export Citation Format

Share Document