scholarly journals Atomic-state-dependent screening model for hot and warm dense plasmas

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Fuyang Zhou ◽  
Yizhi Qu ◽  
Junwen Gao ◽  
Yulong Ma ◽  
Yong Wu ◽  
...  
Keyword(s):  
Radiation Transport ◽  
Atomic State ◽  
Many Body ◽  
Dense Plasmas ◽  
Screening Model ◽  
State Dependent ◽  
Recombination Processes ◽  
Three Body ◽  
Many Body Interactions ◽  
Body Recombination

AbstractAn ion embedded in warm/hot dense plasmas will greatly alter its microscopic structure and dynamics, as well as the macroscopic radiation transport properties of the plasmas, due to complicated many-body interactions with surrounding particles. Accurate theoretically modeling of such kind of quantum many-body interactions is essential but very challenging. In this work, we propose an atomic-state-dependent screening model for treating the plasmas with a wide range of temperatures and densities, in which the contributions of three-body recombination processes are included. We show that the electron distributions around an ion are strongly correlated with the ionic state studied due to the contributions of three-body recombination processes. The feasibility and validation of the proposed model are demonstrated by reproducing the experimental result of the line-shift of hot-dense plasmas as well as the classical molecular dynamic simulations of moderately coupled ultra-cold neutral plasmas. Our work opens a promising way to treat the screening effect of hot and warm dense plasma, which is a bottleneck of those extensive studies in high-energy-density physics, such as atomic processes in plasma, plasma spectra and radiation transport properties, among others.

scholarly journals Full reconstruction of simplicial complexes from binary time-series data

2021 ◽  
Author(s):  
Huan Wang ◽  
Chuang Ma ◽  
Han-Shuang Chen ◽  
Ying-Cheng Lai ◽  
Hai-Feng Zhang
Keyword(s):  
Time Series ◽  
Time Series Data ◽  
Simplicial Complexes ◽  
Series Data ◽  
Many Body ◽  
Stochastic Disturbance ◽  
Binary Time Series ◽  
Full Reconstruction ◽  
Three Body ◽  
Many Body Interactions

Abstract Previous efforts on data-based reconstruction focused on complex networks with pairwise or two-body interactions. There is a growing interest in networks with high-order or many-body interactions, raising the need to reconstruct such networks based on observational data. We develop a general framework combining statistical inference and expectation maximization to fully reconstruct 2-simplicial complexes with two- and three-body interactions based on binary time-series data from social contagion dynamics. We further articulate a two-step scheme to improve the reconstruction accuracy while significantly reducing the computational load. Through synthetic and real-world 2-simplicial complexes, we validate the framework by showing that all the connections can be faithfully identified and the full topology of the 2-simplicial complexes can be inferred. The effects of noisy data or stochastic disturbance are studied, demonstrating the robustness of the proposed framework.

scholarly journals Lattice Dynamics of the High Tc Superconductor ErBa2Cu3O7

1994 ◽  
Vol 47 (1) ◽  
pp. 103 ◽  
Author(s):  
S Mohan ◽  
R Kannan
Keyword(s):  
Lattice Dynamics ◽  
Many Body ◽  
New Approach ◽  
High Tc ◽  
High Tc Superconductor ◽  
Zone Centre ◽  
Three Body ◽  
Many Body Interactions ◽  
Good Agreement ◽  
Infrared Data

The lattice dynamics of the high Tc superconductor ErBa2Cu307 have been investigated in detail with a modified three-body force shell model. The model accounts for the effect of many-body interactions in the lattice potential. The aim of the present work is to treat the various interactions between the ions in generalised way without making them numerically equal. The values of the phonon frequencies calculated at the zone centre by this new approach are in good agreement with the available Raman and infrared data.

scholarly journals Low-order many-body interactions determine the local structure of liquid water

2019 ◽  
Vol 10 (35) ◽  
pp. 8211-8218 ◽  
Author(s):  
Marc Riera ◽  
Eleftherios Lambros ◽  
Thuong T. Nguyen ◽  
Andreas W. Götz ◽  
Francesco Paesani
Keyword(s):  
Liquid Water ◽  
Local Structure ◽  
Quantum Effects ◽  
Many Body ◽  
Three Body ◽  
Many Body Interactions ◽  
Nuclear Quantum Effects ◽  
Structure Of Liquid ◽  
Low Order

Two-body and three-body energies, modulated by higher-body terms and nuclear quantum effects, determine the structure of liquid water and require sub-chemical accuracy that is achieved by the MB-pol model but not by existing DFT functionals.

Laserspektroskopische Untersuchungen an nicht-stabilisierten N2(B3IIg, ν; = 13)-Molekülen / Laser Spectroscopic Studies on Non-stabilized N2(B3IIg, ν; = 13) molecules

1976 ◽  
Vol 31 (6) ◽  
pp. 673-674
Author(s):  
K. H. Becker ◽  
H. Engels ◽  
T. Tatarczyk
Keyword(s):  
Detection Limit ◽  
Emission Spectroscopy ◽  
Spectroscopic Studies ◽  
Rotational Analysis ◽  
Tunable Dye Laser ◽  
Recombination Processes ◽  
Three Body ◽  
Laser Spectroscopic ◽  
Body Recombination ◽  
Better Than

Unstabilized N2(B3IIg, ν = 13) quasi-molecules were analysed by excitation with a tunable dye-laser into the N2(C3IIu) state and observation of the following fluorescence to N2(B3IIg, ν) levels. The quasi-molecules are in equilibrium with the free nitrogen atoms. The detection limit of this technique is 105 molecules/cm3. By the same method, a rotational analysis of molecules stabilized into (B3IIg, ν ≦ 12) levels by three-body recombination processes was achieved with a resolution better than that reached by emission spectroscopy of the Lewis-Rayleigh afterglow

scholarly journals Two- and Three-body Ion-Electron Recombination Rate Coefficients in Neon

1995 ◽  
Vol 48 (3) ◽  
pp. 503 ◽  
Author(s):  
RN Bhave ◽  
R Cooper
Keyword(s):  
Recombination Rate ◽  
Rate Coefficient ◽  
Rate Coefficients ◽  
Electron Recombination ◽  
Wide Range ◽  
Recombination Processes ◽  
Three Body ◽  
Modified Theory ◽  
Body Recombination ◽  
Monatomic Gas

The rates of recombination of electrons with Net ions over a wide range of pressure (1001000 Torr) and at temperatures of 133, 233 and 295 K were measured. Two- and three-body recombination processes were resolved. The observed two-body rate coefficient is lower than earlier reports. The three-body rate measured agrees well with predictions from Flarinery's modified theory by Bates for termolecular ion-electron recombination in a monatomic gas.

scholarly journals Highly Accurate Many-Body Potentials for Simulations of N2O5 in Water: Benchmarks, Development, and Validation

2021 ◽  
Author(s):  
Vinicius Cruzeiro ◽  
Eleftherios Lambros ◽  
Marc Riera ◽  
Ronak Roy ◽  
Francesco Paesani ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Atmospheric Chemistry ◽  
Short Range ◽  
Density Functional ◽  
Coupled Cluster ◽  
Many Body ◽  
Functional Theory ◽  
High Level ◽  
Three Body ◽  
Many Body Interactions

<div><div><div><p>Dinitrogen pentoxide (N2O5) is an important intermediate in the atmospheric chemistry of nitrogen oxides. Although there has been much research, the processes that govern the physical interactions between N2O5 and water are still not fully understood at a molecular level. Gaining quantitative insight from computer simulations requires going beyond the accuracy of classical force fields, while accessing length scales and time scales that are out of reach for high-level quantum chemical approaches. To this end we present the development of MB-nrg many-body potential energy functions for simulations of N2O5 in water. This MB-nrg model is based on electronic structure calculations at the coupled cluster level of theory and is compatible with the successful MB-pol model for water. It provides a physically correct description of long-range many-body interactions in combination with an explicit representation of up to three-body short-range interactions in terms of multidimensional permutationally invariant polynomials. In order to further investigate the importance of the underlying interactions in the model, a TTM-nrg model was also devised. TTM- nrg is a more simplistic representation that contains only two-body short-range interactions represented through Born-Mayer functions. In this work an active learning approach was employed to efficiently build representative training sets of monomer, dimer and trimer structures, and benchmarks are presented to determine the accuracy of our new models in comparison to a range of density functional theory methods. By assessing binding curves, distortion energies of N2O5, and interaction energies in clusters of N2O5 and water, we evaluate the importance of two-body and three-body short-range potentials. The results demonstrate that our MB-nrg model has high accuracy with respect to the coupled cluster reference, outperforms current density functional theory models, and thus enables highly accurate simulations of N2O5 in aqueous environments.</p></div></div></div>

Implications of many-body forces for equations of state at high pressure

1992 ◽  
Vol 339 (1654) ◽  
pp. 395-402 ◽  
Keyword(s):  
High Pressure ◽  
Equations Of State ◽  
Closed Shell ◽  
Molecular Orbital Calculations ◽  
Many Body ◽  
Detonation Products ◽  
Body Forces ◽  
Three Body ◽  
Body Potential ◽  
Many Body Interactions

In this paper we review our recent work concerned with assessing the significance of many-body forces for short-range interactions of closed shell atoms and molecules. Ab initio molecular orbital calculations (of the supermolecule type) have been carried out to determine three-body potentials for the following species: He, Ne, H 2 , N 2 , CO and CO 2 . For He, Ne, H 2 and N 2 we have also carried out calculations of the four-body potential for a limited number of orientations. These studies show that, for all these species, there are significant deviations from pair-wise additivity at short separations. The effect of these many-body interactions on the equation of state for dense fluids (such as detonation products) is being investigated by Monte Carlo simulation, and recent results for high-pressure helium are described.

scholarly journals Highly Accurate Many-Body Potentials for Simulations of N2O5 in Water: Benchmarks, Development, and Validation

2021 ◽  
Author(s):  
Vinicius Cruzeiro ◽  
Eleftherios Lambros ◽  
Marc Riera ◽  
Ronak Roy ◽  
Francesco Paesani ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Atmospheric Chemistry ◽  
Short Range ◽  
Density Functional ◽  
Coupled Cluster ◽  
Many Body ◽  
Functional Theory ◽  
High Level ◽  
Three Body ◽  
Many Body Interactions

<div><div><div><p>Dinitrogen pentoxide (N2O5) is an important intermediate in the atmospheric chemistry of nitrogen oxides. Although there has been much research, the processes that govern the physical interactions between N2O5 and water are still not fully understood at a molecular level. Gaining quantitative insight from computer simulations requires going beyond the accuracy of classical force fields, while accessing length scales and time scales that are out of reach for high-level quantum chemical approaches. To this end we present the development of MB-nrg many-body potential energy functions for simulations of N2O5 in water. This MB-nrg model is based on electronic structure calculations at the coupled cluster level of theory and is compatible with the successful MB-pol model for water. It provides a physically correct description of long-range many-body interactions in combination with an explicit representation of up to three-body short-range interactions in terms of multidimensional permutationally invariant polynomials. In order to further investigate the importance of the underlying interactions in the model, a TTM-nrg model was also devised. TTM- nrg is a more simplistic representation that contains only two-body short-range interactions represented through Born-Mayer functions. In this work an active learning approach was employed to efficiently build representative training sets of monomer, dimer and trimer structures, and benchmarks are presented to determine the accuracy of our new models in comparison to a range of density functional theory methods. By assessing binding curves, distortion energies of N2O5, and interaction energies in clusters of N2O5 and water, we evaluate the importance of two-body and three-body short-range potentials. The results demonstrate that our MB-nrg model has high accuracy with respect to the coupled cluster reference, outperforms current density functional theory models, and thus enables highly accurate simulations of N2O5 in aqueous environments.</p></div></div></div>

Low-Order Many-Body Interactions Determine the Local Structure of Liquid Water

2019 ◽  
Author(s):  
Marc Riera ◽  
Eleftherios Lambros ◽  
Thuong T. Nguyen ◽  
Andreas W. Goetz ◽  
Francesco Paesani
Keyword(s):  
Total Energy ◽  
Liquid Water ◽  
Local Structure ◽  
Great Promise ◽  
Many Body ◽  
Hydrogen Bond Networks ◽  
The Many ◽  
Three Body ◽  
Many Body Interactions ◽  
Structure Of Liquid

<div> <div> <div> <p>Despite its apparent simplicity, water displays unique behavior across the phase diagram which is strictly related to the ability of the water molecules to form dense, yet dynamic, hydrogen- bond networks that continually fluctuate in time and space. The competition between different local hydrogen-bonding environments has been hypothesized as a possible origin of the anomalous properties of liquid water. Through a systematic application of the many-body expansion of the total energy, we demonstrate that the local structure of liquid water at room temperature is determined by a delicate balance between two-body and three-body energies, which is further modulated by higher-order many-body effects. Besides providing fundamental insights into the structure of liquid water, this analysis also emphasizes that a correct representation of two-body and three-body energies requires sub-chemical accuracy that is nowadays only achieved by many-body models rigorously derived from the many-body expansion of the total energy, which thus hold great promise for shedding light on the molecular origin of the anomalous behavior of liquid water. </p> </div> </div> </div>

Low-Order Many-Body Interactions Determine the Local Structure of Liquid Water

2019 ◽  
Author(s):  
Marc Riera ◽  
Eleftherios Lambros ◽  
Thuong T. Nguyen ◽  
Andreas W. Goetz ◽  
Francesco Paesani
Keyword(s):  
Total Energy ◽  
Liquid Water ◽  
Local Structure ◽  
Great Promise ◽  
Many Body ◽  
Hydrogen Bond Networks ◽  
The Many ◽  
Three Body ◽  
Many Body Interactions ◽  
Structure Of Liquid

<div> <div> <div> <p>Despite its apparent simplicity, water displays unique behavior across the phase diagram which is strictly related to the ability of the water molecules to form dense, yet dynamic, hydrogen- bond networks that continually fluctuate in time and space. The competition between different local hydrogen-bonding environments has been hypothesized as a possible origin of the anomalous properties of liquid water. Through a systematic application of the many-body expansion of the total energy, we demonstrate that the local structure of liquid water at room temperature is determined by a delicate balance between two-body and three-body energies, which is further modulated by higher-order many-body effects. Besides providing fundamental insights into the structure of liquid water, this analysis also emphasizes that a correct representation of two-body and three-body energies requires sub-chemical accuracy that is nowadays only achieved by many-body models rigorously derived from the many-body expansion of the total energy, which thus hold great promise for shedding light on the molecular origin of the anomalous behavior of liquid water. </p> </div> </div> </div>

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