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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Signatures of non-adiabatic dynamics in the fine-structure state distributions of the OH(X{sup ~}/A{sup ~}) products in the B-band photodissociation of H{sub 2}O

A detailed quantum mechanical characterization of the photodissociation dynamics of H{sub 2}O at 121.6 nm is presented. The calculations were performed using a full-dimensional wave packet method on coupled potential energy surfaces of all relevant electronic states. Our state-to-state model permits a detailed analysis of the OH(X{sup ~}/A{sup ~}) product fine-structure populations as a probe of the non-adiabatic dissociation dynamics. The calculated rotational state distributions of the two Λ-doublet levels of OH(X{sup ~}, v = 0) exhibit very different characteristics. The A′ states, produced mostly via the B{sup ~}→X{sup ~} conical intersection pathway, have significantly higher populations than the A″ counterparts, which are primarily from the B{sup ~}→A{sup ~} Renner-Teller pathway. The former features a highly inverted and oscillatory rotational state distribution, while the latter has a smooth distribution with much less rotational excitation. In good agreement with experiment, the calculated total OH(X{sup ~}) rotational state distribution and anisotropy parameters show clear even-odd oscillations, which can be attributed to a quantum mechanical interference between waves emanating from the HOH and HHO conical intersections in the B{sup ~}→X{sup ~} non-adiabatic pathway. On the other hand, the experiment-theory agreement for the OH(A{sup ~}) fragment is also satisfactory, although some small quantitative differences suggest remaining imperfections of the ab initio based potential energy surfaces.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2005

Dynamic Weakening (Extinction) of Simple Hydrocarbon-air Counterflow Diffusion Flames by Oscillatory Inflows

This study of laminar non-premixed HC-air flames used an Oscillatory-input Opposed Jet Burner (OOJB) system developed from a previously well-characterized 7.2-mm Pyrex-nozzle OJB system. Over 600 dynamic Flame Strength (FS) measurements were obtained on unanchored (free-floating) laminar Counterflow Diffusion Flames (CFDF's). Flames were stabilized using plug inflows having steady-plus-sinusoidal axial velocities of varied magnitude, frequency, f, up to 1600 Hz, and phase angle from 0 (most data) to 360 degrees. Dynamic FS is defined as the maximum average air input velocity (U(sub air), at nozzle exit) a CFDF can sustain before strain-induced extinction occurs due to prescribed oscillatory peak-to-peak velocity inputs superimposed on steady inputs. Initially, dynamic flame extinction data were obtained at low f, and were supported by 25-120 Hz Hot-Wire cold-flow velocity data at nozzle exits. Later, expanded extinction data were supported by 4-1600 Hz Probe Microphone (PM) pk/pk P data at nozzle exits. The PM data were first obtained without flows, and later with cold stagnating flows, which better represent speaker-diaphragm dynamics during runs. The PM approach enabled characterizations of Dynamic Flame Weakening (DFW) of CFDF's from 8 to 1600 Hz. DFW was defined as % decrease in FS per Pascal of pk/pk P oscillation, namely, DFW = - 100 d(U(sub air) / U(sub air),0Hz) / d(pkpk P). The linear normalization with respect to acoustic pressure magnitude (and steady state (SS) FS) led to a DFW unaffected by strong internal resonances. For the C2H4/N2-air system, from 8 to 20 Hz, DFW is constant at 8.52 plus or minus 0.20 (% weakening)/Pa. This reflects a quasi-steady flame response to an acoustically induced dU(sub air)/dP. Also, it is surprisingly independent of C2H4/N2 mole fraction due to normalization by SS FS. From 20 to approximately 150 Hz, the C2H4/N2 air-flames weakened progressively less, with an inflection at approximately 70 Hz, and became asymptotically insensitive (DFW approximately 0) at approximately 300 Hz, which continued to 1600 Hz. The DFW of CH4-air flames followed a similar pattern, but showed much greater weakening than C2H4/N2-air flames; i.e., the quasi-steady DFW (8 to approximately 15 Hz) was 44.3 %/Pa, or approximately 5x larger, even though the 0 Hz (SS) FS was only 3.0 x smaller. The quasi-steady DFW's of C3H8-air and C2H6-air were intermediate at 34.8 and 20.9 %Pa, respectively. The DFW profiles of all four fuels, at various frequencies, correlated well but non-linearly with respective SS FS's. Notably, the DFW profile for C3H8 air fell more rapidly in the range greater than 15 to 60 Hz, compared with the 1- and 2-carbon fuels. This may indicate a shift in chemical kinetics, and/or O2 transport to a flame that moved closer to the fuel-side. In conclusion, Dynamic Flame Weakening limits appear significant and unique for each fuel, and correlate closely, but non-linearly, with Steady-State Flame Strengths at any given frequency. For reasons unknown, the dynamic flames didn't weaken more at intermediate frequencies (e.g., at 20-50 Hz) than they did at low frequencies (less than 15 Hz), where quasi-steady weakening appears to dominate. Quasi-steady flame weakening ostensibly represents a transient input strain rate maximum that just exceeds the steady-state strain-rate-limited extinction limit for a few cycles. Clearly, further detailed mechanistic understanding is needed in the fall-off region.

Pellett, G.↗
DOE OSTI2026

Atomically Resolved Acoustic Dynamics Coupled with Magnetic Order in a Van der Waals Antiferromagnet

Magnetoelastic coupling in van der Waals (vdW) magnetic materials enables a unique interplay between the spin and lattice degrees of freedom. Characterizing the elastic responses with atomic and femtosecond resolution across the magnetic transition is essential for guiding the design of magnetically tunable actuators and strain-mediated spintronic devices. Here, ultrafast X-ray diffraction employed at a free-electron laser reveals that the atomic displacements, wave vectors, and dispersion relations of acoustic phonon modes in a vdW antiferromagnet FePS3 are coupled with the magnetic order, by tracking both in-plane and out-of-plane Bragg peaks upon optical excitation across the Néel temperature (TN). One transverse mode shows that a quasi-out-of-plane atomic displacement undergoes a significant directional change across TN. Its quasi-in-plane wave vector is derived by comparing the measured sound velocity and the first-principles calculations. The other transverse mode is an interlayer shear acoustic mode whose amplitude is strongly enhanced in the antiferromagnetic phase, exhibiting eight times stronger amplitude than the longitudinal acoustic mode below TN. The atomically resolved characterization of acoustic phonon dynamics that couple with magnetic ordering opens opportunities for harnessing unique magnetoelastic coupling in vdW magnets on ultrafast timescales.

coherent acoustic phonons↗
DOE OSTI2012

Multiscale Analysis of Nonlinear Systems Using Computational Topology

Computational Homology in Fluids: M. Schatz, K. Mischaikow. This effort focused on characterizing both the structure and dynamics of complex spatio-temporal flows that arise in thermal convection. Microstructure Characterization: T. Wanner, K. Mischaikow. We extended our previous work on studying the time evolution of patterns associated with phase separation in conserved concentration fields. Probabilistic Homology Validation: W. Kalies, T. Wanner, K. Mischaikow. Our above mentioned work on microstructure characterization is based on numerically studying the homology of certain sublevel sets of a function, whose evolution is described by deterministic or stochastic evolution equations. Computational Homology and Dynamics: W. Kalies, T. Wanner, K. Mischaikow. Topological methods can be used to rigorously describe the dynamics of nonlinear systems. We are approaching this problem from several perspectives and through a variety of systems. Stress Networks in Polycrystals: T. Wanner. Together with E. Fuller (NIST) and D. Saylor (FDA) we have characterized stress networks in polycrystals. This part of the project is aimed at developing homological metrics which can aid in distinguishing not only microstructures, but also derived mechanical response fields. Microstructure-Controlled Drug Release: K. Mischaikow, T. Wanner. This part of the project is concerned with the development of topological metrics in the context of controlled drug delivery systems, such as drug-eluting stents. We are particularly interested in developing metrics which can be used to link the processing stage to the resulting microstructure, and ultimately to the achieved system response in terms of drug release profiles. Microstructure of Fuel Cells: W. Kalies, K. Mischaikow. In collaboration with P. Voorhees (Northwestern Univ.) and M. Gameiro (Rutgers) we have been using our computational homology software to analyze the topological structure of the void, metal and ceramic components of a Solid Oxide Fuel Cell.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2011

H{sub 2}/N{sub 2} plasma damage on porous dielectric SiOCH film evaluated by in situ film characterization and plasma diagnostics

This study investigates the mechanism of H{sub 2}/N{sub 2} plasma ashing damage of porous SiOCH films. Porous SiOCH films were treated by a H{sub 2}/N{sub 2} plasma using a 100-MHz capacitively coupled plasma etcher. The impact of ions, radicals, and vacuum ultraviolet radiation on the porous SiOCH films was investigated using in situ bulk analysis techniques such as spectroscopic ellipsometry and Fourier-transform infrared spectroscopy and ex situ film characterization techniques such as dynamic secondary ion mass spectrometry and x-ray photoelectron spectroscopy. In addition, plasma analysis including vacuum ultraviolet absorption spectroscopy was performed. The film characterization and plasma analysis show that the extraction of methyl by H radicals was enhanced by light while N radicals were responsible for inhibit the extraction of Si-CH{sub 3} bonds by forming nitride layer. The H{sub 2}/N{sub 2} plasma damage mechanism is discussed based on characterization of the film and plasma diagnostics.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1990

A Hankel singular value approach for identification of low level dynamics in flexible structures

The intensity of dynamics in a flexible structure is characterized by its Hankel singular values. Low level dynamics may be caused by generic properties of a structure or by its actuator and sensor configurations. In the latter case, it is shown that the dynamics can significantly be amplified by small perturbations of actuator and/or sensor configurations. In the presented examples, the variations of sensor configuration of 0.05 or less caused an increase of Hankel singular values of order 1000. This approach is useful for model reduction and model order determination in the presence of noise.

Gawronski, W.↗
NASA NTRS1999

MRI Measurements and Granular Dynamics Simulation of Segregation of Granular Mixture

A counter intuitive axial segregation phenomenon in a rotating horizontal cylinder has recently captured attention of many researchers in different disciplines. There is a growing consensus that the interplay between the particle dynamics and the evolution of the internal structure during the segregation process must be carefully investigated. Magnetic resonance imaging (MRI) has been used to non-invasively obtain much needed dynamic/static information such as velocity and concentration profiles, and it has proven to be capable of depicting the evolution of segregation processes. Segregation in a rotating cylinder involves two processes: the first is to transport small particles in the radial direction to form a radial core, and the second is to transform the radial core into axially segregated bands. Percolation and/or "stopping" have been proposed as mechanisms for the radial segregation. As to mechanisms for axial band formation, much less is known. The difference in the dynamic angle of repose has been proposed to segregate different components in the axial direction. Recently, Hill and Kakalios have reported that particles mix or demix depending upon the competition between diffusion and preferential drift whose order can be determined by the dynamic angle of repose through the adjustment of the rotation rate. We claim that the dynamic angle of repose could be one of the causes, however, it fails to offer reasonable explanations for certain aspects of the axial migration. For example, we always observe that the radial segregation precedes the axial segregation and small particles migrate in the radial direction to form an axially extended radial core. It then transforms into axially segregated bands. By definition, the effects of the dynamic angle of repose are restricted near the free surface where the flowing layer is present. However, during the process of transforming from the radially segregated core to axially segregated bands, small particles located in the deep core region, which is untouched by the flowing layer, also completely disappear. Usually, the dynamics angle of repose are uniquely defined for individual species to characterize particle properties, and the dynamic angle of repose thus defined provides little information for the dynamic angle of repose of the mixture since the concentration ratio and the internal packing structure do not remain the same during the segregation processes. Under microgravity environment, the dynamics angle of repose argument does not hold since there is simply no flowing layer to influence/determine the preferred directions of segregation. We have thus designed an experiment so that the effects of the dynamic angle of repose can be minimized by filling the cylinder almost completely full. Small particles still formed a radial core and also migrated to form axial bands. As ground based experiments we have designed and conducted both 2D and 3D segregation experiments. The 2D experiments are performed using a thin cylinder (the gap between two end caps is about 5 mm) filled with different combinations of particles. The 3D experiments are conducted with a long cylinder of its length and diameter of 27cm and 7cm, respectively. Results of 2D experiments indicate that different mechanisms govern particle motion in regions near and far from the axis of rotation. Results of 3D experiments indicate that a series of collapses of microstructures of particle packing (micro-collapses) may be responsible for the creation of voids for small particles to migrate through in the axial direction. We have successfully eliminated the dynamic angle of repose as a cause for segregation, however, by almost completely filling the cylinder with the particles, we have lost an opportunity to investigate a possibility of particle "mobility" being a cause for segregation which requires a flowing surface but not the difference in the angle of repose. This is currently being investigated.

Nakagawa, M.↗
DOE OSTI2025

Elucidating lipid nanoparticle properties and structure through biophysical analyses

Designing lipid nanoparticle (LNP) delivery systems with specific targeting, potency and minimal side effects is crucial for their clinical use. However, traditional characterization methods, such as dynamic light scattering, cannot accurately quantify physicochemical properties of LNPs and how these are influenced by the lipid composition and mixing method. Here, we structurally characterize polydisperse LNP formulations by applying emerging solution-based biophysical methods that have higher resolution and provide biophysical data beyond size and polydispersity. These techniques include sedimentation velocity analytical ultracentrifugation, field-flow fractionation followed by multiangle light scattering and size-exclusion chromatography in line with synchrotron small-angle X-ray scattering. Here, we show that LNPs have intrinsic polydispersity in size, RNA loading and shape, which depend on both the formulation technique and the lipid composition. Lastly, we predict LNP transfection in vitro and in vivo by examining the relationship between mRNA translation and physicochemical characteristics. Solution-based biophysical methods will be essential for determining LNP structure–function relationships, facilitating the creation of new design rules for LNPs.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Charge transport network dynamics in molecular aggregates

Due to the nonperiodic nature of charge transport in disordered systems, generating insight into static charge transport networks, as well as analyzing the network dynamics, can be challenging. Here, we apply time-dependent network analysis to scrutinize the charge transport networks of two representative molecular semiconductors: a rigid n-type molecule, perylenediimide, and a flexible p-type molecule, bBDT(TDPP)2. Simulations reveal the relevant timescale for local transfer integral decorrelation to be ~100 fs, which is shown to be faster than that of a crystalline morphology of the same molecule. Using a simple graph metric, global network changes are observed over timescales competitive with charge carrier lifetimes. These insights demonstrate that static charge transport networks are qualitatively inadequate, whereas average networks often overestimate network connectivity. Finally, a simple methodology for tracking dynamic charge transport properties is proposed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Soil Microbiome Dynamics During Pyritic Mine Tailing Phytostabilization: Understanding Microbial Bioindicators of Soil Acidification

Challenges to the reclamation of pyritic mine tailings arise from in situ acid generation that severely constrains the growth of natural revegetation. While acid mine drainage (AMD) microbial communities are well-studied under highly acidic conditions, fewer studies document the dynamics of microbial communities that generate acid from pyritic material under less acidic conditions that can allow establishment and support of plant growth. This research characterizes the taxonomic composition dynamics of microbial communities present during a 6-year compost-assisted phytostabilization field study in extremely acidic pyritic mine tailings. A complementary microcosm experiment was performed to identify successional community populations that enable the acidification process across a pH gradient. Taxonomic profiles of the microbial populations in both the field study and microcosms reveal shifts in microbial communities that play pivotal roles in facilitating acidification during the transition between moderately and highly acidic conditions. The potential co-occurrence of organoheterotrophic and lithoautotrophic energy metabolisms during acid generation suggests the importance of both groups in facilitating acidification. Taken together, this research suggests that key microbial populations associated with pH transitions could be used as bioindicators for either sustained future plant growth or for acid generation conditions that inhibit further plant growth.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Dynamical Evolution of Pedestal Parameters in ELMy H-mode in the National Spherical Torus Experiment

Characterizations of the pedestal parameter dynamics throughout the edge localized mode (ELM) cycles are performed on the National Spherical Torus Experiment (NSTX, (Ono et al 2000 Nucl. Fusion 40 557)). A clear buildup of the pedestal height between ELMs is observed for three different plasma currents. This buildup tends to saturate at low and medium plasma currents. Similarly, the pedestal width increases with no clear evidence of saturation during an ELM cycle. The maximum pedestal gradient increases as a function of plasma current, reaches a nominal value after the ELM crash, and remains constant until the end of the ELM cycle. The pedestal height just prior to the onset of ELM is shown to increase quadratically with plasma current. The pedestal width (Delta) scales as Delta = 0.17 root beta(ped)(theta). with the poloidal beta at the top of the pedestal. Coherent density fluctuations strongly increasing at the plasma edge are observed to be maximum after the ELM crash and to decay during the rest of the ELM cycle. Finally, the evolution of the pedestal height and width during the ELM cycle as well as the scaling with I(p) of the pedestal pressure prior to the onset ELM are found to be qualitatively consistent with the peeling-ballooning theory.

Diallo, A↗
DOE OSTI2011

Dynamical Evolution of Pedestal Parameters in ELMy H-mode in the National Spherical Torus Experiment

Characterizations of the pedestal parameter dynamics throughout the edge localized modes(ELM) cycles are performed on the National Spherical Torus Experiment (NSTX, [M. Ono et al., Nucl. Fusion 40, 557 (2000)]). A clear buildup of the pedestal height is observed between ELMs for three different plasma currents, which tends to saturate prior to the onset of ELM at low and medium plasma current. Similarly, the pedestal width increases with no clear evidence of saturation during an ELM cycle. The maximum pedestal gradient increases as a function of plasma current, reaches a nominal value after the ELM crash, and remains constant until the end of the ELM cycle. The pedestal height just prior to the onset of ELM is shown to increase quadratically with plasma current. The pedestal width Δ is proportional to the square-root of the poloidal β at the top of the pedestal. Coherent density fluctuations strongly increasing at the plasma edge are observed to be maximum after the ELM crash and to decay during the rest of the ELM cycle. Finally, the pedestal parameters evolution during the ELM cycle as well as the scaling with Ip of the pedestal pressure prior to the onset ELM are found to be qualitatively consistent with the peeling ballooning theory.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Operando measurement of lattice strain in internal combustion engine components by neutron diffraction

Significance Internal combustion engine components experience extreme thermomechanical cycling during operation, and the continuing need to improve engine efficiency while maintaining or improving reliability drives the development of lightweight materials with improved thermal and mechanical integrity. Understanding the behavior of new materials in dynamic operation requires operando characterization tools, but conventional in situ measurements of material behavior during real engine operation are very limited, and no practical means exist to replicate such extreme dynamics for ex situ study. In this work, we demonstrate that the penetrating power of neutrons can provide noninvasive measurement of lattice strains inside components of a firing engine, enabling the operando study of complex load states and thermal gradients throughout the solid materials.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Quantification of microtubule stutters: dynamic instability behaviors that are strongly associated with catastrophe

Microtubules (MTs) are cytoskeletal fibers that undergo dynamic instability (DI), a remarkable process involving phases of growth and shortening separated by stochastic transitions called catastrophe and rescue. Dissecting DI mechanism(s) requires first characterizing and quantifying these dynamics, a subjective process that often ignores complexity in MT behavior. We present a Statistical Tool for Automated Dynamic Instability Analysis (STADIA) that identifies and quantifies not only growth and shortening, but also a category of intermediate behaviors that we term “stutters.” During stutters, the rate of MT length change tends to be smaller in magnitude than during typical growth or shortening phases. Quantifying stutters and other behaviors with STADIA demonstrates that stutters precede most catastrophes in our in vitro experiments and dimer-scale MT simulations, suggesting that stutters are mechanistically involved in catastrophes. Related to this idea, we show that the anticatastrophe factor CLASP2γ works by promoting the return of stuttering MTs to growth. STADIA enables more comprehensive and data-driven analysis of MT dynamics compared with previous methods. The treatment of stutters as distinct and quantifiable DI behaviors provides new opportunities for analyzing mechanisms of MT dynamics and their regulation by binding proteins.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

The linear and non-linear characterization of dust ion acoustic mode in complex plasma in presence of dynamical charging of dust

A systematic theoretical investigation has been carried out on the role of dust charging dynamics on the nature and stability of DIA (Dust Ion Acoustic) mode in complex plasma. The study has been made for both linear and non-linear scale regime of DIA mode. The observed results have been characterized in terms of background plasma responses towards dust surface responsible for dust charge fluctuation, invoking important dusty plasma parameters, especially the ion flow speed and dust size. The linear analyses confirm the nature of instability in DIA mode in presence of dust charge fluctuation. The instability shows a damping of DIA mode in subsonic flow regime followed by a gradual growth in instability in supersonic limit of ion flow. The strength of non-linearity and their existence domain is found to be driven by different dusty plasma parameters. As dust is ubiquitous in interstellar medium with plasma background, the study also addresses the possible effect of dust charging dynamics in gravito-electrostatic characterization and the stability of dust molecular clouds especially in proto-planetary disc. The observations are influential and interesting towards the understanding of dust settling mechanism and formation of dust environments in different regions in space.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Characterization of CO2 behavior on rutile TiO2 (110) surface

The dynamic behavior of carbon dioxide (CO2) adsorbed on the rutile TiO2 (110) surface is studied by dispersion-corrected density functional theory (DFT) and combined ab initio molecular dynamics (AIMD). Understanding he behavior of CO2 is important regarding possible applications for treating CO2 in current environmental problems along with the consideration as a renewable energy source. Concerning the ability as a redusible support of TiO2 surface, a fundamental understanding of the interaction between CO2 and TiO2 surface will help extending the possibile applications. In the current study, CO2 interaction and dynamics behavior on the TiO2 surface is characterized including he effect of the oxygen vacancy (OV) defect. Also the coverage dependence of CO2 behavior is investigated since more contribution of the intermolecular interaction among CO2 molecules can be expected as the coverage increasing. This work is supported by the US Department of Energy (DOE), Office of Basic Science, Division of Chemical Sciences, Geosicences and Biosciences. Pacific Northwest National Laboratory (PNNL) is multiprogram national laboratory operated for DOE by Battelle. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

ab initio molecular dynamics↗
DOE OSTI2016

Hydration level dependence of the microscopic dynamics of water adsorbed in ultramicroporous carbon

Even when not functionalized intentionally, most carbon materials are not hydrophobic and readily adsorb water molecules from atmospheric water vapor. We have equilibrated an ultramicroporous carbon at several levels of relative humidity, thereby attaining various hydration levels. The water molecules were adsorbed on the pore walls (but did not fill completely the pore volume) and thus could be better described as hydration, or surface, rather than confined, water. We used quasielastic neutron scattering to perform a detailed investigation of the dependence of microscopic dynamics of these adsorbed water species on the hydration level and temperature. The behavior of hydration water in ultramicroporous carbon clearly demonstrates the same universal traits that characterize surface (hydration) water in other materials that are surface-hydrated. In addition, unless special treatment is intentionally applied to ultramicroporous carbon, the species filling its pores in various applications, ranging from hydrogen molecules to electrolytes, likely find themselves in contact with non-freezing water molecules characterized by rich microscopic dynamics.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Accelerated Molecular Dynamics Methods [Slides]

The molecular dynamics method, although extremely powerful for materials simulations, is limited to times scales of roughly one microsecond or less. On longer time scales, dynamical evolution typically consists of infrequent events, which are usually activated processes. This course is focused on understanding infrequent-event dynamics, on methods for characterizing infrequent-event mechanisms and rate constants, and on methods for simulating long time scales in infrequent-event systems, emphasizing the recently developed accelerated molecular dynamics methods (hyperdynamics, parallel replica dynamics, and temperature accelerated dynamics). Some familiarity with basic statistical mechanics and molecular dynamics methods will be assumed.

74 ATOMIC AND MOLECULAR PHYSICS↗