AN ELASTIC CONTINUUM MODEL FOR FULLERENE ENERGETICS

1995 ◽  
Vol 09 (25) ◽  
pp. 1649-1655 ◽  
Author(s):  
XIA XIAOYU ◽  
LIU JI-XING ◽  
OU-YANG ZHONG-CAN
Keyword(s):  
Ab Initio ◽  
Minimal Surfaces ◽  
Continuum Model ◽  
Numerical Results ◽  
Elastic Theory ◽  
Elastic Continuum ◽  
Positive Evidence ◽  
Empirical Potential ◽  
Fluid Membranes ◽  
Good Agreement

By analogy with the elastic theory of solid shells1 and fluid membranes,2 it has been suggested that fullerenes, at least large ones, might somehow resemble the classic elastic continuum, as indicated by Schnur.3 Some related works dealt with nanotubes do show positive evidence for this suggestion.4 Here we propose an elastic continuum model appropriate to graphite-like networks. Applying it to various shapes of fullerenes, such as spheres, tubes, tori, and minimal surfaces, we found good agreement between this model and previous numerical results given by approaches of ab initio or empirical potential. Furthermore, this model enables one to understand the puzzling phenomena such as why Schwarzite P216 and Schwarzite D216 have nearly identical bending energies while their geometric forms are very different (see Fig. 1). The prospect of this model is also discussed.

Interatomic Potential for Condensed Phases and Bulk Defects in Silicon

1997 ◽  
Vol 469 ◽  
Author(s):  
J. F. Justo ◽  
M. Z. Bazant ◽  
E. Kaxiras ◽  
V. V. Bulatov ◽  
S. Yip
Keyword(s):  
Ab Initio ◽  
Interatomic Potential ◽  
Interatomic Interaction ◽  
Condensed Phases ◽  
Defect Structures ◽  
Empirical Potential ◽  
Partial Dislocations ◽  
Functional Forms ◽  
Three Body ◽  
Good Agreement

ABSTRACTWe present a new empirical potential for silicon which is a considerable improvement over existing models in describing structures away from equilibrium, such as bulk defects. The interatomic interaction is described by two- and three-body terms using theoretically motivated functional forms which emphasize chemical and physical trends. The numerical parameters in the functional forms are obtained by fitting to several ab initio calculations, which include bulk phases and defect structures. The model is tested to core properties of partial dislocations in the glide set {111}, which are not included in the database, and gives results in very good agreement with ab initio calculations. This is the only known potential capable of describing the structure of both the 30°- and 90°-partial dislocations.

scholarly journals The influence of exocyclic lone pairs on the bonding and geometry of type A mesoionic rings

2021 ◽  
Author(s):  
Christopher Antony Ramsden ◽  
Wojciech Piotr Oziminski
Keyword(s):  
Ab Initio ◽  
Type A ◽  
Nbo Analysis ◽  
Ring Systems ◽  
X Ray ◽  
X Ray Crystallography ◽  
Bond Model ◽  
Lone Pairs ◽  
Mp2 Calculations ◽  
Good Agreement

AbstractBased on structures determined by X-ray crystallography, ab initio MP2 calculations on type A mesoionic rings give geometries in good agreement with observed values. A study of four mesoionic ring systems, each with exocyclic oxygen, nitrogen or carbon groups, shows that the presence and configuration of exocyclic lone pairs significantly influences the geometry and configurational preference. Using a localised bond model and NBO analysis, these effects are rationalised in terms of an anomeric interaction of lone pairs with the antibonding orbitals of adjacent σ bonds. In agreement with experiment, similar effects are calculated for pyran-2-imines.

THEORETICAL CALCULATION OF pKb VALUES FOR ANILINES AND SULFONAMIDE DRUGS IN AQUEOUS SOLUTION

2012 ◽  
Vol 11 (02) ◽  
pp. 283-295 ◽  
Author(s):  
BAHRAM GHALAMI-CHOOBAR ◽  
ALI GHIAMI-SHOMAMI ◽  
PARIA NIKPARSA
Keyword(s):  
Gas Phase ◽  
Continuum Model ◽  
Correlation Equation ◽  
Polarizable Continuum Model ◽  
Free Energies ◽  
Pcm Model ◽  
Solvation Models ◽  
Polarizable Continuum ◽  
Better Than ◽  
Good Agreement

In this work, calculations of p K b values have been performed for aniline and its substituted derivatives and sulfonamide drugs by using Gaussian 98 software package. Gas-phase energies were calculated with HF /6-31 G ** and B3LYP /6-31 G ** levels of theory. Free energies of solvation have been computed using the polarizable continuum model (PCM), conductor-like polarizable continuum model (CPCM) and the integral equation formalism-polarizable continuum model (IEFPCM) at the same levels which have been used for geometry determination in the gas-phase. The results show that the calculated p K b values using the B3LYP /6-31 G ** are better than those using the corresponding HF /6-31 G **. At first, the correlation equation was found to determine the p K b values of the investigated anilines. Then, this correlation equation was used to calculate the p K b values of the sulfonamide drugs. The results obtained indicate that the PCM model is a suitable solvation model for calculating p K b values in comparison to the other solvation models. For the investigated compounds a good agreement between the experimental and the calculated p K b values was also observed.

scholarly journals THE METHOD OF INCREMENTS — A WAVEFUNCTION-BASED AB-INITIO CORRELATION METHOD FOR SOLIDS

2007 ◽  
Vol 21 (13n14) ◽  
pp. 2204-2214 ◽  
Author(s):  
BEATE PAULUS
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Ground State ◽  
Infinite System ◽  
Correlation Energy ◽  
Correlation Method ◽  
Many Body ◽  
Hartree Fock ◽  
The Many ◽  
Good Agreement

The method of increments is a wavefunction-based ab initio correlation method for solids, which explicitly calculates the many-body wavefunction of the system. After a Hartree-Fock treatment of the infinite system the correlation energy of the solid is expanded in terms of localised orbitals or of a group of localised orbitals. The method of increments has been applied to a great variety of materials with a band gap, but in this paper the extension to metals is described. The application to solid mercury is presented, where we achieve very good agreement of the calculated ground-state properties with the experimental data.

Calculating Fundamental Vibrational Frequencies of Rutile by Combining Ab Initio Method with GF Matrix Method

1994 ◽  
Vol 05 (02) ◽  
pp. 299-301
Author(s):  
Lin Libin ◽  
Zheng Xiangyin
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Matrix Method ◽  
Cluster Model ◽  
Normal Modes ◽  
Vibrational Frequencies ◽  
Ab Initio Method ◽  
Environment Factor ◽  
Factor Α ◽  
Good Agreement

Based on cluster model, we have calculated the fundamental vibrational frequencies of rutile by combining ab initio method and Wilson’s GF-matrix method. In the calculation, we have introduced the concept of environment factor α to correct the force field of the cluster model. The results of calculation are in good agreement to the experimental data and the normal modes give us clear physical picture of the crystal vibration.

Contributions to Silicon-Hydrogen Bond-Stretching Frequency in Amorphous Si Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
Z. Jing ◽  
J. L. Whitten ◽  
G. Lucovsky
Keyword(s):  
Experimental Data ◽  
Hydrogen Bond ◽  
Dielectric Constant ◽  
Ab Initio ◽  
Effective Dielectric Constant ◽  
Bond Energies ◽  
Calculated Frequency ◽  
Bond Stretching ◽  
Amorphous Si ◽  
Good Agreement

ABSTRACTWe have performed ab initio calculations and determined the bond-energies and vibrational frequencies of Si-H groups that are: i) attached to Si-atoms as their immediate, and also more distant neighbors; and ii) attached to three O-atoms as their immediate neighbors, but are connected to an all Si-atom matrix. These arrangements simulate bonding geometries on Si surfaces, and the calculated frequency for i) is in good agreement with that of an Si-H group on an Si surface. To compare these results with a-Si:H alloys it is necessary to take into account an additional factor: the effective dielectric constant of the host. We show how to do this, demonstrating the way results of the ab initio calculations should then be compared with experimental data.

On Wall Effects in Cavity Flows

1984 ◽  
Vol 28 (01) ◽  
pp. 70-75
Author(s):  
C. C. Hsu
Keyword(s):  
Numerical Results ◽  
Cavity Flows ◽  
Two Dimensional ◽  
Wall Effects ◽  
Free Jet ◽  
Theoretical Predictions ◽  
Experimental Findings ◽  
Good Agreement

Simple wall correction rules for two-dimensional and nearly two-dimensional cavity flows in closed or free jet water tunnels, based on existing linearized analyses, are made. Numerical results calculated from these expressions are compared with existing experimental findings. The present theoretical predictions are, in general, in good agreement with data.

Periodic wave solution of the Kundu-Mukherjee-Naskar equation in birefringent fibers via the Hamiltonian-based algorithm

2021 ◽  
Author(s):  
Kang-Jia Wang ◽  
Hong-Wei Zhu
Keyword(s):  
Wave Solution ◽  
Bright Light ◽  
Periodic Wave ◽  
Optical Soliton ◽  
Numerical Results ◽  
Periodic Wave Solution ◽  
Soliton Dynamics ◽  
Good Agreement

Abstract The Kundu-Mukherjee-Naskar equation can be used to address certain optical soliton dynamics in the (2+1) dimensions. In this paper, we aim to find its periodic wave solution by the Hamiltonian-based algorithm. Compared with the existing results, they have a good agreement, which strongly proves the correctness of the proposed method. Finally, the numerical results are presented in the form of 3-D and 2-D plots. The results in this work are expected to shed a bright light on the study of the periodic wave solution in physics.

Sign in / Sign up

Export Citation Format

Share Document