scholarly journals On-the-fly determination of active region centers in adaptive-partitioning QM/MM

2020 ◽  
Vol 22 (34) ◽  
pp. 19307-19317
Author(s):  
Zeng-hui Yang
Keyword(s):  
Active Region ◽  
Energy Conservation ◽  
Geometrical Property ◽  
Adaptive Partitioning

The QM/MM partition is determined on-the-fly using any geometrical property as a criterion, while satisfying energy conservation.

On-the-Fly Determination of Active Region Centers in Adaptive-Partitioning QM/MM

2020 ◽  
Author(s):  
Zenghui Yang
Keyword(s):  
Quantum Mechanics ◽  
Active Region ◽  
Molecular Mechanics ◽  
Active Regions ◽  
Available Energy ◽  
Adaptive Partitioning ◽  
Different Levels

Quantum mechanics/molecular mechanics (QM/MM) methods partition the system into active and environmental regions and treat them with different levels of theory, achieving accuracy and efficiency at the same time. Adaptive-partitioning (AP) QM/MM methods allow on-the-fly changes to the QM/MM partitioning of the system. Many of the available energy-based AP-QM/MM methods partition the system according to distances to pre-chosen centers of active regions. For such AP-QM/MM methods, I develop an adaptive-center (AC) method that allows on-the-fly determination of the centers of active regions according to general geometrical or potential-related criteria, extending the range of application of energy-based AP-QM/MM methods to systems where active regions may occur or vanish during the simulation.

scholarly journals On-the-Fly Determination of Active Region Centers in Adaptive-Partitioning QM/MM

2020 ◽  
Author(s):  
Zenghui Yang
Keyword(s):  
Quantum Mechanics ◽  
Active Region ◽  
Molecular Mechanics ◽  
Active Regions ◽  
Available Energy ◽  
Adaptive Partitioning ◽  
Different Levels

Quantum mechanics/molecular mechanics (QM/MM) methods partition the system into active and environmental regions and treat them with different levels of theory, achieving accuracy and efficiency at the same time. Adaptive-partitioning (AP) QM/MM methods allow on-the-fly changes to the QM/MM partitioning of the system. Many of the available energy-based AP-QM/MM methods partition the system according to distances to pre-chosen centers of active regions. For such AP-QM/MM methods, I develop an adaptive-center (AC) method that allows on-the-fly determination of the centers of active regions according to general geometrical or potential-related criteria, extending the range of application of energy-based AP-QM/MM methods to systems where active regions may occur or vanish during the simulation.

Simultaneous quantitative determination of strain and defect profiles within the active region along high-power diode laser bars by micro-photocurrent mapping

2004 ◽  
Vol 27 (1-3) ◽  
pp. 451-454 ◽  
Author(s):  
A. Gerhardt ◽  
J. W. Tomm ◽  
S. Schwirzke-Schaaf ◽  
J. Nagle ◽  
M. Oudart ◽  
...  
Keyword(s):  
Active Region ◽  
Quantitative Determination ◽  
Diode Laser ◽  
High Power ◽  
Power Diode ◽  
High Power Diode Laser

Determination of the dependence of the refractive index of the active region of an injection laser on the carrier density

1991 ◽  
Vol 21 (11) ◽  
pp. 1195-1196 ◽  
Author(s):  
I I Vinogradov ◽  
O V Danilina ◽  
A E Kosykh ◽  
Aleksandr S Logginov
Keyword(s):  
Refractive Index ◽  
Active Region ◽  
Carrier Density ◽  
Injection Laser

Research on the Ratio of Fixed Heating Charges to Total Heating Charges of Residential Buildings in Five Cities of North China

Solar Energy ◽  
2005 ◽  
Author(s):  
Xiumu Fang ◽  
Lixin Gao
Keyword(s):  
Energy Conservation ◽  
North China ◽  
Residential Buildings ◽  
Conservation Performance

The ratio of public heating losses to total heating losses is fixed for a given building. The determination of this ratio is the basis for allocating heating charges fairly and reasonably, and is also the basis for determining the ratio of fixed heating charges to total heating charges. The changing rule of the ratio of public heating losses to total heating losses of 15 residential buildings in north China was researched under different conditions, such as different energy conservation performance, different usage and different layout etc, and drew some referable conclusions.

scholarly journals Speed-Dependent Adaptive Partitioning QM/MM for Displacement Damage Simulations

2020 ◽  
Author(s):  
Zenghui Yang
Keyword(s):  
Active Region ◽  
Ab Initio ◽  
Rapid Change ◽  
Active Regions ◽  
Chem Phys ◽  
Model Systems ◽  
Harsh Environments ◽  
Adaptive Partitioning ◽  
Energy Conserving ◽  
Dependent Potential

Solids receive displacement damages (DD) when interacting with energetic particles, which may happen during the fabrication of semiconductor devices, in harsh environments and in certain analysis techniques. Simulations of the DD generation are usually carried out with classical molecular dynamics (MD), but classical MD does not account for all the effects in DD, as demonstrated by <i>ab initio</i> calculations of model systems in literature. A fully <i>ab initio</i> simulation of the DD generation is impractical due to the large number of atoms involved. In my previous paper [Phys. Chem. Chem. Phys. 22, 19307 (2020)], I developed an adaptive-center (AC) method for adaptive-partitioning (AP) quantum mechanics/molecular mechanics (QM/MM) simulations, allowing the active region centers and the QM/MM partition to be determined on-the-fly for energy-conserving AP-QM/MM methods. I demonstrated that the AC-AP-QM/MM is applicable to the simulation of the DD generation, so that the active regions can be treated with an <i>ab initio</i> method. The AC method was unable to identify the fast-moving recoil ions in the DD generation as active region centers, however, and the accuracy is negatively affected by the rapid change in QM/MM partition of the system. In this paper, I extend the AC method and develop a speed-dependent adaptive-center (SDAC) method for proper AP-QM/MM simulations of DD. The SDAC method is applicable to general problems with speed-dependent active regions, and is compatible with all existing energy-conserving partition-by-distance AP-QM/MM methods. The artifact due to the speed-dependent potential energy surface can be made small by choosing proper criteria. I demonstrate the SDAC method by simulations of the DD generation in bulk Silicon.<br>

scholarly journals Spectropolarimetric analysis of an active region filament

2019 ◽  
Vol 625 ◽  
pp. A128 ◽  
Author(s):  
C. J. Díaz Baso ◽  
M. J. Martínez González ◽  
A. Asensio Ramos
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Active Region ◽  
Spectral Lines ◽  
Component Model ◽  
Vector Magnetic Field ◽  
Solar Filaments ◽  
Magnetic Filed ◽  
The Magnetic Field

Aims. The determination of the magnetic filed vector in solar filaments is made possible by interpreting the Hanle and Zeeman effects in suitable chromospheric spectral lines like those of the He I multiplet at 10 830 Å. We study the vector magnetic field of an active region filament (NOAA 12087). Methods. Spectropolarimetric data of this active region was acquired with the GRIS instrument at the GREGOR telescope and studied simultaneously in the chromosphere with the He I 10 830 Å multiplet and in the photosphere Si I 10 827 Å line. As has been done in previous studies, only a single-component model was used to infer the magnetic properties of the filament. The results are put into a solar context with the help of the Solar Dynamic Observatory images. Results. Some results clearly point out that a more complex inversion had to be performed. First, the Stokes V map of He I does not show a clear signature of the presence of the filament. Second, the local azimuth map follows the same pattern as Stokes V; it appears that polarity of Stokes V is conditioning the inference to very different magnetic fields even with similar linear polarization signals. This indication suggests that the Stokes V could be dominated from below by the magnetic field coming from the active region, and not from the filament itself. This evidence, and others, will be analyzed in depth and a more complex inversion will be attempted in the second part of this series.

Collisionless damping of plasma waves as a real physical phenomenon does not exist

2014 ◽  
Vol 6 (3) ◽  
pp. 1291-1296
Author(s):  
V. N. Soshnikov
Keyword(s):  
Energy Conservation ◽  
Dispersion Equation ◽  
Physical Phenomenon ◽  
Harmonic Wave ◽  
Collisionless Plasma ◽  
Plasma Waves ◽  
Wave Number ◽  
Erroneous Statement ◽  
Complex Dispersion

Trivial logic of collisionless plasma waves is reduced to using complex exponentially damping/growing wave functions to obtain a complex dispersion equation for their wave number 1 k and the decrement/increment 2 k (for a given real frequency  and complex wave number k  k1  ik2 ), whose solutions are ghosts 1 2 k , k which do not have anything to do at 2 k  0 with the real solution of the dispersion equation for the initial exponentially damping/growing real plasma waves with the physically observable quantities 1 2 k , k , for which finding should be added, in this case, the second equation of the energy conservation law. Using a complex dispersion equation for the simultaneous determination of 1 k and 2 k violates the law of energy conservation, leads to a number of contradictions, is logical error, and finally also the mathematical error leading to both erroneous statement on the possible existence of exponentially damping/growing harmonic wave solutions and to erroneous values 1 k and 2 k . Mathematically correct conclusion about the damping/growing of virtual complex waves of collisionless plasma is wrongly attributed to the actual real plasma waves.

High-resolution photography of the solar chromosphere. XXI Determination of the physical conditions in an H-alpha active-region loop

1985 ◽  
Vol 294 ◽  
pp. 697 ◽  
Author(s):  
R. E. Loughhead ◽  
R. J. Bray ◽  
J.-L. Wang
Keyword(s):  
High Resolution ◽  
Active Region ◽  
Solar Chromosphere ◽  
Physical Conditions ◽  
Region Loop
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