Modelling the morphology of minerals by computer

1995 ◽  
Vol 59 (397) ◽  
pp. 607-615 ◽  
Author(s):  
A. L. Rohl ◽  
D. H. Gay
Keyword(s):  
Basal Plane ◽  
Computer Code ◽  
Surface Relaxation ◽  
Complete Agreement ◽  
Growth Morphology ◽  
Bulk Properties ◽  
Hartree Fock ◽  
Surfaces And Interfaces ◽  
First Time ◽  
Effect Of Surface

AbstractA new computer code (MARVIN) has been developed for the simulation of surfaces and interfaces. The models and methodologies employed within the program are briefly discussed. One application of the code, calculating crystal morphologies, is explored using zircon, quartz and α-Al2O3 as examples. The new code enables the use of covalent type force fields and the effect of surface relaxation on the growth morphology to be calculated for the first time. It is found that relaxation does affect the attachment energy but not by a large enough amount to significantly change the growth morphology for the three examples discussed here. Finally, the calculated surface relaxation for the basal plane of α-Al2O3 is found to be in complete agreement with Hartree-Fock ab initio calculations, verifying that the potentials, which are derived from bulk properties, transfer well to this surface.

scholarly journals Неэмпирические расчеты структуры и устойчивости нанотрубок на основе монохалькогенидов галлия

2020 ◽  
Vol 62 (6) ◽  
pp. 908
Author(s):  
В.В. Карпов ◽  
А.В. Бандура ◽  
Р.А. Эварестов
Keyword(s):  
Strain Energy ◽  
Density Functional ◽  
Density Functional Method ◽  
Computer Code ◽  
Functional Method ◽  
Dispersion Interactions ◽  
Hartree Fock ◽  
Armchair Nanotubes ◽  
Different Diameters ◽  
First Time

For the first time first-principles calculations were performed to get the dependences of strain energy and band gap of achiral nanotubes obtained by rolling up monolayers of gallium (II) sulfide and selenide. The hybrid density functional method (with 13% of the Hartree-Fock exchange) within the CRYSTAL17 computer code was used. The empirical Grimme correction was applied to describe the dispersion interactions between layers accurately. As a result of simulations of nanotubes with different chirality and different diameters, the minimum diameters of the stable single-walled nanotubes were determined, which retain the continuity of the chemical bonds on the outer nanotube surface. It was shown that the strain energy dependence on a diameter obeys a classical law of inverse squares and is the same for «zigzag» and «armchair» nanotubes.

Calculations of Atomic and Electronic Structure for (100) Surfaces of SrTiO3 Perovskite

2002 ◽  
Vol 718 ◽  
Author(s):  
R. I. Eglitis ◽  
E. Heifets ◽  
E. A. Kotomin ◽  
G. Borstel
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Computer Code ◽  
Basis Set ◽  
Surface Relaxation ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Atomic And Electronic Structure

AbstractWe present and discuss main results of the calculations for the surface relaxation and rumpling of SrTiO3 surfaces with TiO2 and SrO terminations using a wide variety of methods of modern computational physics and chemistry, including the shell model (SM) and ab initio methods based on Hartree-Fock (HF) and Density Functional Theory (DFT). The HF and DFT formalisms with different exchange-correlation functionals are implemented into Crystal-98 computer code using a Gaussian-type basis set. We demonstrate that a hybrid B3PW formalism gives the best results for the bulk SrTiO3 properties. Results are compared with previous ab initio plane-wave LDA calculations and LEED experiments. Our calculations demonstrate an increase of the covalency effects between Ti and O atoms near the surface.

scholarly journals New Transition and Energy Levels of Three-Times Ionized Krypton (Kr IV)

Atoms ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 48
Author(s):  
M. Raineri ◽  
M. Gallardo ◽  
J. Reyna Almandos ◽  
A. G. Trigueiros ◽  
C. J. B. Pagan
Keyword(s):  
Transition Probabilities ◽  
Energy Levels ◽  
Pulsed Discharge ◽  
Core Polarization ◽  
Polarization Effects ◽  
Hartree Fock ◽  
Theta Pinch ◽  
New Energy ◽  
First Time

A capillary pulsed-discharge and a theta-pinch were used to record Kr spectra in the region of 330–4800 Å. A set of 168 transitions of these spectra were classified for the first time. We extended the analysis to twenty-five new energy levels belonging to 3s23p24d, 3s23p25d even configurations. We calculated weighted transition probabilities (gA) for all of the experimentally observed lines and lifetimes for new energy levels using a relativistic Hartree–Fock method, including core-polarization effects.

scholarly journals Extended analysis of Xe VII and Xe VIII

2017 ◽  
Vol 95 (9) ◽  
pp. 805-810 ◽  
Author(s):  
M. Raineri ◽  
M. Gallardo ◽  
J. Reyna Almandos ◽  
C.J.B. Pagan ◽  
R. Sarmiento
Keyword(s):  
Light Source ◽  
Energy Levels ◽  
Excited Configuration ◽  
Pulsed Discharge ◽  
Hartree Fock ◽  
The Core ◽  
New Energy ◽  
Extended Analysis ◽  
First Time ◽  
Atomic Parameters

A pulsed discharge light source to study the six and seven times ionized xenon spectra in the 419–4642 Å region was used. A set of 40 transitions of Xe VII and 25 transitions of Xe VIII were classified for the first time. We revised the values for the previously known energy levels and extended the analysis for Xe VII to 10 new energy levels belonging to 5s6d, 5s7s and 5s7p, 4d95s25p even and odd configurations, respectively. Seven new energy levels of the core excited configuration 4d95s5d of Xe VIII are presented. For the prediction of the atomic parameters, energy levels, and transition, relativistic Hartree–Fock calculations were used.

An Investigation on the Fine Structure Levels in the Ground State Configuration for the Antimony Anion

2014 ◽  
Vol 69 (8-9) ◽  
pp. 397-402
Author(s):  
Leyla Özdemir ◽  
Sadiye Tuna
Keyword(s):  
Fine Structure ◽  
Ground State ◽  
Transition Probabilities ◽  
Relativistic Effects ◽  
Electric Quadrupole ◽  
Radiative Transition ◽  
Ground State Configuration ◽  
Hartree Fock ◽  
First Time ◽  
State Configuration

We have investigated the correlation, relativistic, and isotope shift effects on the fine structure levels in the ground state configuration for the antimony anion ( Sb-). Energies and radiative transition probabilities (for magnetic dipole, M1, and electric quadrupole, E2) have been obtained using the multiconfiguration Hartree-Fock method within the framework of the Breit-Pauli Hamiltonian. Therefore, the most important configuration interaction and relativistic effects have been included. Comparisons with other available works are presented. For some M1 and E2 lines the considered transition probabilities are reported for the first time

STRUCTURAL AND ELECTRONIC PROPERTIES OF c-BN(110) SURFACE AND SURFACE POINT DEFECTS

2006 ◽  
Vol 17 (06) ◽  
pp. 795-803 ◽  
Author(s):  
HATICE KÖKTEN ◽  
ŞAKIR ERKOÇ
Keyword(s):  
Point Defects ◽  
Cubic Boron Nitride ◽  
Vacancy Formation ◽  
Surface Point ◽  
Hartree Fock ◽  
Structural And Electronic Properties ◽  
Structure Surface ◽  
Surface Vacancy ◽  
First Time ◽  
Formation Energies

The surface structure, surface energy, and surface vacancy formation energy for B and N vacancy of the cubic boron nitride (c-BN)(110) surface have been investigated by performing Hartree-Fock and DFT calculations. Results are compared with available literature values. The vacancy formation energies [unrelaxed [Formula: see text] and relaxed (Ef)] are reported for the first time for c-BN(110).

Electronically addressable nanomechanical switching of i-motif DNA origami assembled on basal plane HOPG

2015 ◽  
Vol 51 (74) ◽  
pp. 14111-14114 ◽  
Author(s):  
R. Campos ◽  
S. Zhang ◽  
J. M. Majikes ◽  
L. C. C. Ferraz ◽  
T. H. LaBean ◽  
...  
Keyword(s):  
Basal Plane ◽  
Dna Origami ◽  
First Time

Here, a pH-induced nanomechanical switching of i-motif structures incorporated into DNA origami bound onto cysteamine-modified basal plane HOPG was electronically addressed, demonstrating for the first time the electrochemical read-out of the nanomechanics of DNA origami.

PECULIAR SURFACE SIZE-EFFECTS IN NaCl NANO-CRYSTALS

2013 ◽  
Vol 20 (01) ◽  
pp. 1350001 ◽  
Author(s):  
N. KANA ◽  
S. KHAMLICH ◽  
J. B. KANA KANA ◽  
M. MAAZA
Keyword(s):  
Sodium Chloride ◽  
Size Effects ◽  
Basal Plane ◽  
Size Dependence ◽  
Size Variation ◽  
Metallic Behavior ◽  
Vaporization Temperature ◽  
Theoretical Predictions ◽  
First Time ◽  
Major Target

While the major target of this contribution was the stabilization of the theoretically predicted CsCl form of the sodium chloride which could exhibit a singular and peculiar metallic behavior, this study took advantage of the nano-scaled aspect of the synthesized NaCl to report for the first time in the literature, the size dependence of various thermodynamic parameters of nano-sized NaCl crystals. More accurately, size effect on vaporization temperature of NaCl nano-crystals has been conducted on NaCl nanoparticles exhibiting a net shape anisotropy. The investigated nano-scaled NaCl particles were micrometric in the basal plane while nanometric in the transversal direction. An obvious size variation of the vaporization temperature is observed experimentally in agreement with the theoretical predictions. Specifically, the vaporization temperature T V decreases from almost 1680 (bulk) to 1290 K (nano-sized): a relative decrease of nearly 23.5%. The T V ≈ T(χ) size dependence where χ is the relative molar concentration of the initial NaCl precursor was found to follow the form T V (° C ) ≈ 750.7χ2 - 340.1χ + 1002.

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