Thermochemical Quantities Research Articles

Large-eddy simulation of multiphase combustion jet in cross-flow using flamelet model

In this work, large-eddy simulations of pulverized coal combustion are conducted using the flamelet model, in which the devolatilization, char surface reactions, radiation and flame-wall interactions (FWI) are all considered. The mixings between the oxidizer and the volatiles/char off-gases are described with two mixture fractions Zvol and Zchar, while the interphase heat transfer and progress of reactions are described with the manifolds of total enthalpy He and reaction progress variable YPV, respectively. The turbulence-chemistry interactions are considered with the presumed probability density functions. Standard pulverized coal combustion submodels are used to characterize the coal combustion sub-processes of devolatilization, char surface reactions, radiation, etc. Characteristics of pulverized coal combustion jet in cross-flow (JICF) are analyzed in detail. Particularly, the effects of the flame-flame interactions (FFI) and the wall heat losses (WHL) on the pulverized coal flame structure and thermo-chemical quantities distributions are studied through both qualitative and quantitative analyses. The results show that the overall flame temperature with twin jets in cross-flow (TJICF) is higher than that with single jet in cross-flow (SJICF) due to the FFI. The gas velocities in different directions have different sensitivities to the FFI, and the particle residence time/trajectory is influenced by the FFI. Three stages of FFI are identified, i.e., separated flames, merging flames and a merged flame. When the effects of WHL are neglected, the flame front becomes more wrinkling, the flame base moves towards the injectors, and the coal particles are ignited earlier. The pulverized coal flame structure at the lee-side of the flame front is more complicated than that at the leading-edge due to the different flow dynamics, and many burning pockets can be observed at the lee-side.

Formulation of Small Test Sets Using Large Test Sets for Efficient Assessment of Quantum Chemistry Methods.

In the present study, we have examined in detail literature data of deviations for a wide range of (mainly) DFT methods for the extensive MGCDB82 set (∼4400 data points) of main-group thermochemical quantities. We use the data and standard statistical techniques (lasso regularization and forward selection) to devise the MG8 model for linearly combining assessment results of a collection of small data sets to accurately estimate the MAD of MGCDB82. The MG8 model contains a total of 64 data points representing noncovalent interactions, isomerization energies, thermochemical properties, and barrier heights. It is thus well suited for rapid evaluation of new quantum chemistry procedures. We propose that a value of ∼4 kJ mol-1 for an estimated MAD by the MG8 model (EMADMG8) to be an initial indicator of a highly robust quantum chemistry method, with large deviations occurring mainly for properties (such as heats of formation) that are known to be difficult to accurately compute. For methods with larger EMADs, we emphasize the importance of more thorough testing, as these methods are likely to have a larger number of outliers, and it may be less trivial to anticipate circumstances under which large deviations occur. In relation to this aspect, we have applied the same generally applicable statistical techniques to further formulate small-data-set models for assessing the accuracy for some properties that are not covered by MG8 nor by MGCDB82. They include the MOR13 model for metal-organic reactions, the SBG5 model for semiconductor band gaps, and MB13 for stress-testing methods with artificial species.

Evaluation of different flamelet tabulation methods for laminar spray combustion

In this work, three different flamelet tabulation methods for spray combustion are evaluated. Major differences among these methods lie in the treatment of the temperature boundary conditions of the flamelet equations. Particularly, in the first tabulation method (“M1”), both the fuel and oxidizer temperature boundary conditions are set to be fixed. In the second tabulation method (“M2”), the fuel temperature boundary condition is varied while the oxidizer temperature boundary condition is fixed. In the third tabulation method (“M3”), both the fuel and oxidizer temperature boundary conditions are varied and set to be equal. The focus of this work is to investigate whether the heat transfer between the droplet phase and gas phase can be represented by the studied tabulation methods through a priori analyses. To this end, spray flames stabilized in a three-dimensional counterflow are first simulated with detailed chemistry. Then, the trajectory variables are calculated from the detailed chemistry solutions. Finally, the tabulated thermo-chemical quantities are compared to the corresponding values from the detailed chemistry solutions. The comparisons show that the gas temperature cannot be predicted by “M1” with only a mixture fraction and reaction progress variable being the trajectory variables. The gas temperature can be correctly predicted by both “M2” and “M3,” in which the total enthalpy is introduced as an additional manifold. In “M2,” variations of the oxidizer temperature are considered with a temperature modification technique, which is not required in “M3.” Interestingly, it is found that the mass fractions of the reactants and major products are not sensitive to the representation of the interphase heat transfer in the flamelet chemtables, and they can be correctly predicted by all tabulation methods. By contrast, the intermediate species CO and H2 in the premixed flame reaction zone are over-predicted by all tabulation methods.

An a priori study of different tabulation methods for turbulent pulverised coal combustion

In many practical pulverised coal combustion systems, different oxidiser streams exist, e.g. the primary- and secondary-air streams in the power plant boilers, which makes the modelling of these systems challenging. In this work, three tabulation methods for modelling pulverised coal combustion are evaluated through an a priori study. Pulverised coal flames stabilised in a three-dimensional turbulent counterflow, consisting of different oxidiser streams, are simulated with detailed chemistry first. Then, the thermo-chemical quantities calculated with different tabulation methods are compared to those from detailed chemistry solutions. The comparison shows that the conventional two-stream flamelet model with a fixed oxidiser temperature cannot predict the flame temperature correctly. The conventional two-stream flamelet model is then modified to set the oxidiser temperature equal to the fuel temperature, both of which are varied in the flamelets. By this means, the variations of oxidiser temperature can be considered. It is found that this modified tabulation method performs very well on prediction of the flame temperature. The third tabulation method is an extended three-stream flamelet model that was initially proposed for gaseous combustion. The results show that the reference gaseous temperature profile can be overall reproduced by the extended three-stream flamelet model. Interestingly, it is found that the predictions of major species mass fractions are not sensitive to the oxidiser temperature boundary conditions for the flamelet equations in the a priori analyses.

Use of Low-Cost Quantum Chemistry Procedures for Geometry Optimization and Vibrational Frequency Calculations: Determination of Frequency Scale Factors and Application to Reactions of Large Systems.

We have assessed the performance of a variety of low-cost computational quantum chemistry procedures (semiempirical, pure-DFT, and screened-exchange DFT methods) for computing molecular geometries and thermochemical quantities associated with the vibrational frequencies. Frequency scale factors for zero-point vibrational energies and thermal corrections for 298 K enthalpies and 298 K entropies have been determined. In absolute terms, for small to medium-sized molecules, all procedures perform reasonably well. Semiempirical methods have mean absolute deviations (MADs) of ∼15 kJ mol-1 for total enthalpies and free energies. For DFT procedures, hybrid DFT generally performs better than pure DFT. Remarkably, the N12 pure functional shows very good performances (MADs ∼ 3 kJ mol-1) that are comparable to those for hybrid functionals. An examination of the basis set effect indicates N12/3-21G* and N12/6-31G(d) to be cost-effective for geometry optimization and vibrational frequency calculations, but the use of minimal basis sets leads to very large MADs for the calculated thermochemical quantities. Further testing with reaction energies of large systems shows that, by exploiting cancellation of systematic deviations, although the deviations can be very substantial in absolute terms (>100 kJ mol-1), those for relative energies are markedly reduced (∼10 kJ mol-1). This enables the use of even semiempirical procedures to obtain geometries and vibrational frequencies with reasonable accuracy in cases where the use of more expensive procedures is computationally prohibitive.

Numerical investigation of the effects of volatile matter composition and chemical reaction mechanism on pulverized coal combustion characteristics

Volatile matter is generally treated as postulated substance or a combination of different species because the detailed chemical compounds in volatile matter are not yet completely understood. However, very few studies investigate the effects of volatile matter composition and chemical reaction mechanism on the pulverized coal combustion characteristics. In this work, numerical simulations of pulverized coal laminar flames stabilized in a two-dimensional counterflow are conducted to examine these effects on the behaviors of pulverized coal combustion. The results show that the pulverized coal combustion characteristics can be changed considerably by slightly varying the species compositions in volatile matter. The pulverized coal flame structure calculated with large hydrocarbon volatile matter can be largely reproduced by a specific combination of light species. It is also shown that the pulverized coal flame structure cannot be correctly predicted by a single-step mechanism. Finally, it is found that both the stable thermo-chemical quantities and some intermediate species (e.g. OH) mass fractions are not sensitive to the choice of chemical reaction mechanism when detailed chemistry is considered.

Evaluation of flamelet/progress variable model for laminar pulverized coal combustion

In the present work, the flamelet/progress variable (FPV) approach based on two mixture fractions is formulated for pulverized coal combustion and then evaluated in laminar counterflow coal flames under different operating conditions through both a priori and a posteriori analyses. Two mixture fractions, Zvol and Zchar, are defined to characterize the mixing between the oxidizer and the volatile matter/char reaction products. A coordinate transformation is conducted to map the flamelet solutions from a unit triangle space (Zvol, Zchar) to a unit square space (Z, X) so that a more stable solution can be achieved. To consider the heat transfers between the coal particle phase and the gas phase, the total enthalpy is introduced as an additional manifold. As a result, the thermo-chemical quantities are parameterized as a function of the mixture fraction Z, the mixing parameter X, the normalized total enthalpy Hnorm, and the reaction progress variable YPV. The validity of the flamelet chemtable and the selected trajectory variables is first evaluated in a priori tests by comparing the tabulated quantities with the results obtained from numerical simulations with detailed chemistry. The comparisons show that the major species mass fractions can be predicted by the FPV approach in all combustion regions for all operating conditions, while the CO and H2 mass fractions are over-predicted in the premixed flame reaction zone. The a posteriori study shows that overall good agreement between the FPV results and those obtained from detailed chemistry simulations can be achieved, although the coal particle ignition is predicted to be slightly earlier. Overall, the validity of the FPV approach for laminar pulverized coal combustion is confirmed and its performance in turbulent pulverized coal combustion will be tested in future work.

A Thermodynamic Framework Bridging the Composition and Temperature Dependence of Bulk Modulus With Enthalpy of Mixing

The intrinsic thermodynamic links that exist between thermochemical and thermophysical quantities, especially their temperature, pressure, and composition dependence, have seldom been analyzed in sufficient detail in literature. In this connection, an attempt is made to establish a thermodynamic bridge, relating Δo H mix, the standard enthalpy of mixing with Δo B T , the change in isothermal bulk modulus as a result of alloying and its composition and temperature dependence. In essence, by adopting the standard regular and subregular solution approximations to the composition dependence of mixing enthalpy; and furthermore, incorporating separately the configurational (Δo S conf) and vibrational (Δo S Vib) entropy contributions to mixing Gibbs energy change (Δo G mix), simple models have been derived for the composition and temperature variations of excess bulk modulus ΔB T . In particular, a regular or subregular solution analog of the composition variation of ΔB T is shown to be possible if Δo H mix could be described likewise. The vibrational entropy contribution to ΔB T is found to be important only when the change in Gruneisen parameter during alloying turns to be significant. The practical utility of the theoretical framework developed in this study has been demonstrated by applying it to disordered fcc Cu1−x Ni x alloys, wherein it is shown that Δo H mix and Δo B T are linearly correlated, as predicted by the theory.

How to computationally calculate thermochemical properties objectively, accurately, and as economically as possible

Abstract We have developed the WnX series of quantum chemistry composite protocols for the computation of highly-accurate thermochemical quantities with advanced efficiency and applicability. The W1X-type methods have a general accuracy of ~3–4 kJ mol−1 and they can currently be applied to systems with ~20–30 atoms. Higher-level methods include W2X, W3X and W3X-L, with the most accurate of these being W3X-L. It can be applied to molecules with ~10–20 atoms and is generally accurate to ~1.5 kJ mol−1. The WnX procedures have opened up new possibilities for computational chemists in pursue of accurate thermochemical values in a highly-productive manner.

Numerical investigation of coal flamelet characteristics in a laminar counterflow with detailed chemistry

The characteristics of flamelets in coal flames stabilized in a laminar counterflow are numerically investigated with detailed chemistry. The behaviors of coal flamelet are compared with those of the gas flamelet. In addition, the effects of strain rate, coal particle mass flow rate and coal particle size on the behaviors of coal flamelet are studied in both the physical space and the mixture fraction space. The results show that the characteristics of coal flamelet are significantly different from those of the gas flamelet. On the one hand, unlike the monotonicity of the gaseous mixture fraction, the coal particle mixture fraction is non-monotonic due to the interphase mass transfer. On the other hand, due to the non-monotonicity of coal particle mixture fraction, the thermo-chemical quantities in the coal flame cannot be uniquely identified by a single variable of mixture fraction as those in the gas flame. It is also found that the strain rate, coal particle mass flow rate and coal particle size have significantly effects on the behaviors of coal flamelet.

Accurate Theoretical Thermochemistry for Fluoroethyl Radicals.

An accurate coupled-cluster (CC) based model chemistry was applied to calculate reliable thermochemical quantities for hydrofluorocarbon derivatives including radicals 1-fluoroethyl (CH3-CHF), 1,1-difluoroethyl (CH3-CF2), 2-fluoroethyl (CH2F-CH2), 1,2-difluoroethyl (CH2F-CHF), 2,2-difluoroethyl (CHF2-CH2), 2,2,2-trifluoroethyl (CF3-CH2), 1,2,2,2-tetrafluoroethyl (CF3-CHF), and pentafluoroethyl (CF3-CF2). The model chemistry used contains iterative triple and perturbative quadruple excitations in CC theory, as well as scalar relativistic and diagonal Born-Oppenheimer corrections. To obtain heat of formation values with better than chemical accuracy perturbative quadruple excitations and scalar relativistic corrections were inevitable. Their contributions to the heats of formation steadily increase with the number of fluorine atoms in the radical reaching 10 kJ/mol for CF3-CF2. When discrepancies were found between the experimental and our values it was always possible to resolve the issue by recalculating the experimental result with currently recommended auxiliary data. For each radical studied here this study delivers the best heat of formation as well as entropy data.

LES of pulverized coal combustion with a multi-regime flamelet model

It is well known that premixed and non-premixed flamelets coexist in the combustion system, especially for multiphase combustion (Luo et al., 2011; Bai et al., 2016). In this work, a multi-regime combustion model for partially premixed multiphase combustion (2PMC) is developed in the framework of large eddy simulation (LES). In this model, the multi-regime combustion mode is decomposed into two pure combustion regimes (i.e. premixed and non-premixed) through combustion regime indicator. Different combustion models are chosen for different combustion regimes. For example, for premixed combustion regime, the flamelet generated manifold (FGM) tabulation method in combination with the artificially thickened flame (ATF) approach is used. For non-premixed combustion regime, on the other hand, the thermo-chemical quantities will be extracted from the non-premixed chemtable generated by the flamelet/progress variable (FPV) approach. The proposed multi-regime flamelet model is then extended to adapt to the pulverized coal combustion (PCC) and applied to a laboratory-scale pulverized coal jet flame. The simulation results show that the percentage of the volume-weighted premixed combustion regime of this studied flame is up to 18%. Quantitative comparisons between the experimental data and the numerical results with the present multi-regime flamelet model, the FPV model, and the Eddy Break Up (EBU) model shows that the proposed multi-regime flamelet model has several advantages. It performs better than the FPV model in the regions where premixed combustion mode prevails and also much better than the EBU model in species concentration prediction.

Frequency Scale Factors for Some Double-Hybrid Density Functional Theory Procedures: Accurate Thermochemical Components for High-Level Composite Protocols

In the present study, we have obtained geometries and frequency scale factors for a number of double-hybrid density functional theory (DH-DFT) procedures. We have evaluated their performance for obtaining thermochemical quantities [zero-point vibrational energies (ZPVE) and thermal corrections for 298 K enthalpies (ΔH298) and 298 K entropies (S298)] to be used within high-level composite protocols (using the W2X procedure as a probe). We find that, in comparison with the previously prescribed protocol for optimization and frequency calculations (B3-LYP/cc-pVTZ+d), the use of contemporary DH-DFT methods such as DuT-D3 and DSD-type procedures leads to a slight overall improved performance compared with B3-LYP. A major strength of this approach, however, lies in the better robustness of the DH-DFT methods in that the largest deviations are notably smaller than those for B3-LYP. In general, the specific choices of the DH-DFT procedure and the associated basis set do not drastically change the performance. Nonetheless, we find that the DSD-PBE-P86/aug'-cc-pVTZ+d combination has a very slight edge over the others that we have examined, and we recommend its general use for geometry optimization and vibrational frequency calculations, in particular within high-level composite methods such as the higher-level members of the WnX series of protocols. The scale factors determined for DSD-PBE-P86/aug'-cc-pVTZ+d are 0.9830 (ZPVE), 0.9876 (ΔH298), and 0.9923 (S298).

Formation, stability, and solubility of metal oxide nanoparticles: Surface entropy, enthalpy, and free energy of ferrihydrite

Ferrihydrite (Fh) is an excellent model for understanding nanoparticle behavior in general. Moreover, Fh is one of the most important Fe (hydr) oxides in nature. Fh particles can be extremely small leading to a very high reactive surface area that changes its chemical potential, strongly affecting the solubility, nucleation, and stability. These characteristics can be coupled to the interfacial Gibbs free energy, being γ=0.186±0.01Jm−2 for Fh. The surface free energy has a relatively large contribution of surface entropy (−TSsurf=+0.079±0.01Jm−2). The surface entropy is primarily related to the formation of surface groups by chemisorption of water (−17.1Jmol−1K−1), for Fh equivalent with +0.064±0.002Jm−2 at a surface loading NH2O=12.6μmolm−2. The entropy contribution of physisorbed water has been estimated by analyzing, as model, the surface enthalpy, entropy, and Gibbs free energy of the principal interfaces of H2O, i.e. ice–water–gas. It is about 20% of the contribution of chemisorbed water.The surface enthalpy of Fh is exceptionally low (Hsurf=+0.107±0.01Jm−2), which can be explained by surface depletion (SD) of relatively unstable Fe polyhedra, or similarly, by additional surface loading of the non-depleted mineral core with specific Fe polyhedra for stabilization. The experimental enthalpy of Fh formation varies linearly with the surface area and correctly predicts the enthalpy value for the mineral core (−405.2±1.2kJmol FeO3/2), being similar to the literature value for Fh as virtual bulk material (−406.7±1.5kJmol FeO3/2) obtained with MO/DFT computations. The thermochemical quantities of the mineral core and surface are essentially the same for the entire range of Fh samples, in line with the SD model.The solubility of Fh suspensions as a whole may differ from the behavior of individual particles due to polydispersity. For 2-line Fh, the overall solubility is logKso∼−38.5±0.1 and for prolongedly aged 6-line Fh, logKso∼−39.5±0.1. The smallest Fh particles in a suspension react according to the Ostwald–Freundlich equation (RTΔlnKso=2/3 γA), but the suspension as a whole apparently reacts according to the Ostwald equation (RTΔlnKso=γA). This difference can be explained by the observed linear relation between the minimum (dmin) and mean (dmean) particle size (dmin=2/3 dmean) in Fh suspensions.With best estimates for the surface entropy of goethite, hematite, and lepidocrocite, predictions show that Fh becomes thermodynamically unstable above a diameter of ∼8.0nm at 298K, allowing formation of nano-goethite and nano-hematite, as experienced experimentally at Ostwald ripening. More generally, one observes that metal (hydr) oxides with the highest chemical stability also have the highest mean surface Gibbs free energy, which can be considered as the scientific explanation of the empirical rule of Ostwald–Lussac. In addition, it is shown that the surface Gibbs free energies of metal (hydr) oxides increase with the mean metal coordination number of oxygen in the lattices following the order: oxides>oxyhydroxides>hydroxides.

Mapping the genome of meta-generalized gradient approximation density functionals: the search for B97M-V.

A meta-generalized gradient approximation density functional paired with the VV10 nonlocal correlation functional is presented. The functional form is selected from more than 10(10) choices carved out of a functional space of almost 10(40) possibilities. Raw data come from training a vast number of candidate functional forms on a comprehensive training set of 1095 data points and testing the resulting fits on a comprehensive primary test set of 1153 data points. Functional forms are ranked based on their ability to reproduce the data in both the training and primary test sets with minimum empiricism, and filtered based on a set of physical constraints and an often-overlooked condition of satisfactory numerical precision with medium-sized integration grids. The resulting optimal functional form has 4 linear exchange parameters, 4 linear same-spin correlation parameters, and 4 linear opposite-spin correlation parameters, for a total of 12 fitted parameters. The final density functional, B97M-V, is further assessed on a secondary test set of 212 data points, applied to several large systems including the coronene dimer and water clusters, tested for the accurate prediction of intramolecular and intermolecular geometries, verified to have a readily attainable basis set limit, and checked for grid sensitivity. Compared to existing density functionals, B97M-V is remarkably accurate for non-bonded interactions and very satisfactory for thermochemical quantities such as atomization energies, but inherits the demonstrable limitations of existing local density functionals for barrier heights.

Molecular thermodynamics of metabolism: quantum thermochemical calculations for key metabolites.

The present work is the first of a series of papers aiming at a coherent and unified development of the thermodynamics of metabolism and the rationalization of feasibility analysis of metabolic pathways. The focus in this part is on high-level quantum chemical calculations of the thermochemical quantities of relatively heavy metabolites such as amino acids/oligopeptides, nucleosides, saccharides and their derivatives in the ideal gas state. The results of this study will be combined with the corresponding hydration/solvation results in subsequent parts of this work in order to derive the desired thermochemical quantities in aqueous solutions. The above metabolites exist in a vast conformational/isomerization space including rotational conformers, tautomers or anomers exhibiting often multiple or cooperative intramolecular hydrogen bonding. We examine the challenges posed by these features for the reliable estimation of thermochemical quantities. We discuss conformer search, conformer distribution and averaging processes. We further consider neutral metabolites as well as protonated and deprotonated metabolites. In addition to the traditional presentation of gas-phase acidities, basicities and proton affinities, we also examine heats and free energies of ionic species. We obtain simple linear relations between the thermochemical quantities of ions and the formation quantities of their neutral counterparts. Furthermore, we compare our calculations with reliable experimental measurements and predictive calculations from the literature, when available. Finally, we discuss the next steps and perspectives for this work.

Low-energy photoelectron imaging of HS2 anion.

Low-energy photoelectron imaging of HS2 (-) has been investigated, which provides the vibrational frequencies of the ground state as well as the first excited state of HS2. It allows us to determine more accurate electron affinity of HS2, 1.9080 ± 0.0018 eV. Combined with Frank-Condon simulation, the vibrational features have been unveiled related to S-S stretching and S-S-H bending modes for the ground state and S-S stretching, S-S-H bending, and S-H stretching modes for the first excited state. Photoelectron angular distributions are mainly characteristic of electron detachment from two different molecular orbitals (MOs) in HS2 (-). With the aid of accurate electron affinity value of HS2, corresponding thermochemical quantities can be accessed.

Large eddy simulations of the HIFiRE scramjet using a compressible flamelet/progress variable approach

In this study, large eddy simulations (LES) of supersonic combustion using a compressible flamelet/progress variable (CFPV) approach are performed for the HIFiRE scramjet at Mach 8 flight conditions. The LES results show good agreement with the ground test experimental measurements. The combustion model is based on an efficient flamelet approach, where compressibility corrections are devised based on assumed functional forms of important thermo-chemical quantities. Specifically, the source term of the progress variable is rescaled with the local density and temperature in the LES, leading to improved predictions relative to existing flamelet models. A modified equilibrium wall-model, capable of predicting the viscous heating, is used in the viscous near-wall region. Temperature near the wall increases significantly due to viscous heating, enhancing the reaction rate and heat-release. This is shown to be a crucial step for accurately predicting the pressure rise in the combustor.

Inside Cover, Volume 114, Issue 17

International Journal of Quantum ChemistryVolume 114, Issue 17 p. iii-iv Cover ImageFree Access Inside Cover, Volume 114, Issue 17 First published: 12 July 2014 https://doi.org/10.1002/qua.24739AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Thermochemical quantities must be accompanied by uncertainties that unambiguously convey their believed accuracy, which combines the achieved precision and perceived trueness. Branko Rusic reports on page 1097 (DOI: 10.1002/qua.24605) that the uncertainties of electronic structure results can be quantified either by benchmarking (Type A) or estimation (Type B), and should adhere to the universally accepted standard in thermochemistry of expressing them as 95% confidence intervals. The ubiquitous Mean Absolute Deviation (MAD) severely underestimates the conventional uncertainty used in thermochemistry. Volume114, Issue17Special Issue: VIIIth Congress of the International Society for Theoretical Chemical PhysicsSeptember 5, 2014Pages iii-iv RelatedInformation

Language-oriented rule-based reaction network generation and analysis: Algorithms of RING

The underlying algorithms of the language interface and post-generation analysis modules in RING, a network generation and analysis tool, are discussed. The front-end is a domain-specific reaction language developed with Silver, a meta-language based on attribute grammars. The language compiler translates user inputs written as a program into internal instructions, catches syntactic and semantic errors, and performs domain-specific optimization to speed up execution. In addition to generating reaction networks, RING allows post-processing analysis options to: (a) obtain reaction pathways and overall mechanisms from initial reactants to desired products using graph traversal algorithms, (b) group together isomers to reduce the size of the network through a novel molecule hashing technique, (c) calculate thermochemical quantities through semi-empirical methods such as group additivity, and (d) formulate and solve kinetic models of the entire or lumped complex network based on a rule-based kinetics specification scheme.