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Massobrio, Carlo; Celino, Massimo; Pasquarello, Alfredo

doi:10.1103/physrevb.70.174202

Cited by 38 publications

(52 citation statements)

References 46 publications

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“…The Ge-Se system has been the subject of considerable interest from the theoretical point of view and comparisons of the neutron diffraction data presented herein with the results obtained from (especially ab initio) molecular dynamics simulations are given elsewhere for liquid GeSe [97,98], liquid GeSe 2 [99][100][101][102][103][104][105][106] [78,79] and for molten GeSe 2 at 784°C (broken curves) [39,40]. The inset shows the low-k region of S BT CC ðkÞ on an enlarged scale.…”

Section: Discussionmentioning

confidence: 91%

Structure of liquids and glasses in the Ge–Se binary system

Salmon

2007

Journal of Non-Crystalline Solids

104

128

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Section: Discussionmentioning

confidence: 91%

Structure of liquids and glasses in the Ge–Se binary system

Salmon

2007

Journal of Non-Crystalline Solids

104

128

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“…45 Extensive first-principles molecular dynamics investigations, in which S CC (k) is calculated from the atomic positions and S ZZ (k) is calculated by taking into account the valence-electron density, show that these fluctuations in charge do not occur. 29,102 Instead, the absence of charge fluctuations over intermediate range distances provides a constraint on the network properties.…”

Section: Concentration Fluctuations On An Intermediate Length Scalementioning

confidence: 99%

Identifying and characterising the different structural length scales in liquids and glasses: an experimental approach

Salmon

Zeidler

2013

Phys. Chem. Chem. Phys.

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The structure of several network-forming liquids and glasses is considered, where a focus is placed on the detailed information that is made available by using the method of neutron diffraction with isotope substitution (NDIS). In the case of binary network glass-forming materials with the MX 2 stoichiometry (e.g. GeO 2 , GeSe 2 , ZnCl 2 ), two different length scales at distances greater than the nearest-neighbour distance manifest themselves by peaks in the measured diffraction patterns. The network properties are influenced by a competition between the ordering on these ''intermediate'' and ''extended'' length scales, which can be manipulated by changing the chemical identity of the atomic constituents or by varying state parameters such as the temperature and pressure. The extended-range ordering, which describes the decay of the pair-correlation functions at large-r, can be represented by making a pole analysis of the Ornstein-Zernike equations, an approach that can also be used to describe the large-r behaviour of the pair-correlation functions for liquid and amorphous metals where packing constraints are important. The first applications are then described of the NDIS method to measure the detailed structure of aerodynamically-levitated laser-heated droplets of ''fragile'' glass-forming liquid oxides (CaAl 2 O 4 and CaSiO 3 ) at high-temperatures (B2000 K) and the structure of a ''strong'' network-forming glass (GeO 2 ) under pressures ranging from ambient to B8 GPa. The high-temperature experiments show structural changes on multiple length scales when the oxides are vitrified. The high-pressure experiment offers insight into the density-driven mechanisms of network collapse in GeO 2 glass, and parallels are drawn with the high-pressure behaviour of silica glass. Finally, the hydrogen-bonded network of water is considered, where the first application of the method of oxygen NDIS is used to measure the structures of light versus heavy water and a difference of C0.5% is found between the O-D and O-H intra-molecular bond lengths. The experimental data are best matched by using path integral molecular dynamics simulations with a flexible anharmonic water model, and the results support a competing quantum effects model for water in which its structural and dynamical properties are governed by an offset between intra-molecular and inter-molecular quantum contributions.

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“…23 In a series of previous papers, we had adopted the PW scheme due to Perdew and Wang as a generalized gradient approximation. 13,14,15,16,22,35,36 This amounts to go beyond the local density approximation (LDA) by using an analytic representation of the correlation energy ε c (ρ) for a uniform electron gas. This representation allows for variations of ε c (ρ) as a function of ρ and the spin polarization.…”

Section: Theoretical Modelmentioning

confidence: 99%

Improved modeling of liquidGeSe2: Impact of the exchange-correlation functional

2009

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The structural properties of liquid GeSe2 are studied by using first-principles molecular dynamics in conjuncton with the Becke, Lee, Yang and Parr (BLYP) generalized gradient approximation for the exchange and correlation energy. The results on partial pair correlation functions, coordination numbers, bond angle distributions and partial structure factors are compared with available experimental data and with previous first-principle molecular dynamics results obtained within the Perdew and Wang (PW) generalized gradient approximation for the exchange and correlation energy. We found that the BLYP approach substantially improves upon the PW one in the case of the short-range properties. In particular, the Ge−Ge pair correlation function takes a more structured profile that includes a marked first peak due to homopolar bonds, a first maximum exhibiting a clear shoulder and a deep minimum, all these features being absent in the previous PW results. Overall, the amount of tetrahedral order is significantly increased, in spite of a larger number of Ge−Ge homopolar connections. Due to the smaller number of miscoordinations, diffusion coefficients obtained by the present BLYP calculation are smaller by at least one order of magnitude than in the PW case.

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Charge fluctuations and concentration fluctuations at intermediate-range distances in the disordered network-forming materialsSiO2,Si
Carlo Massobrio
¹
,
Massimo Celino
²
,
Alfredo Pasquarello
³

Cited by 38 publications

References 46 publications

Structure of liquids and glasses in the Ge–Se binary system

Structure of liquids and glasses in the Ge–Se binary system

Identifying and characterising the different structural length scales in liquids and glasses: an experimental approach

Improved modeling of liquidGeSe2: Impact of the exchange-correlation functional

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Charge fluctuations and concentration fluctuations at intermediate-range distances in the disordered network-forming materialsSiO2,SiCarlo Massobrio1, Massimo Celino2, Alfredo Pasquarello3

Cited by 38 publications

References 46 publications

Structure of liquids and glasses in the Ge–Se binary system

Structure of liquids and glasses in the Ge–Se binary system

Identifying and characterising the different structural length scales in liquids and glasses: an experimental approach

Improved modeling of liquidGeSe2: Impact of the exchange-correlation functional

Contact Info

Product

Resources

About

Charge fluctuations and concentration fluctuations at intermediate-range distances in the disordered network-forming materialsSiO2,Si
Carlo Massobrio
¹
,
Massimo Celino
²
,
Alfredo Pasquarello
³