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We present the self-assembly of DNA nanostars having three, four and five arms into a gel phase using a bead-spring coarse-grained model.

Using molecular dynamics simulations, we report phase separation in a 50:50 mixture of hot(active) and cold(passive) dumbbells which interact by Lennard-Jones potential. The ratio of the temperature difference between hot and cold dumbbells to the temperature of cold dumbbells is a measure of the activity $\chi$ of the system. From constant density simulations, we observe that the hot and cold dumbbells phase separate at high activity ratio ($\chi > 5.80$). The critical activity of dumbbells is higher compared to that of a mixture of hot and cold Lennard-Jones monomers ($\chi > 3.44$). The extent of phase separation is greater for high density. As activity increases, the cold dumbbells cohere to form a large cluster indicating increased phase separation which is quantified by an order parameter. On phase separation, the effective volume of the hot dumbbells increases which leads to the increase in their entropy which is calculated by two-phase thermodynamic(2PT) method. Also, the phase separation pushes the cold dumbbells to form a dense cluster which develops crystalline order with pre-dominantly FCC and HCP packing, but the individual dumbbells have random orientations. The high kinetic pressure of hot dumbbells is balanced by the virial pressure of cold dumbbells. The simulation of the non-equilibrium system at different ratios of number of hot dumbbells to cold dumbbells reveals that the critical activity decreases with increase in fraction of hot dumbbells., Comment: 12 pages, 16 figures

The role of urea as a kinetic promoter for the growth of CO2 hydrates is revealed for the first time using molecular dynamics simulations. Analysis of simulation trajectories shows that urea plays two important roles in the growth process: increasing mass transport of CO2 and catalyzing cage formation at the solid–liquid interface.

It is well understood that tetrahydrofuran (THF) molecules are able to stabilize the large cages (51264) of structure II to form the THF hydrate with empty small cages even at atmospheric pressure....

We report for the first time an excited-state (EX) tuning approach to accurately predict vertical emissions (VEs) based on the study of 36 medium and large organic molecules (∼66 heavy atoms) used ...

The consideration of directional hydrogen bonding in the COSMO-SAC model based on the minima in the molecular electrostatic potential has been shown to significantly improve the description of solv...

The knowledge on the deviation of local composition from bulk composition has been proven to be powerful for modeling the excess thermodynamic properties of liquid mixtures. However, the exact solution to the local compositions is available for a few cases, such as the one-dimensional (1D) lattice fluids and for certain two-dimensional (2D) lattice fluids (the Ising models). We discover that the long-range correlation in the fluid structure, which is not present in 1D but is important in 2D, is the main reason for the complication of getting the exact local compositions for general 2D lattice fluids. In this work, a general approach for calculating the local compositions in 2D lattice fluids is developed. We show that for any stripe-like 2D lattices, the long-range correlations can be avoided by transforming the system to a multicomponent 1D system. The local compositions of such a system can be determined by minimization of the free energy of the mixture. We found that the local compositions, energy, and...

The role of urea as a kinetic promoter for the growth of CO2 hydrates is revealed for the first time using molecular dynamics simulations. Analysis of simulation trajectories shows that urea plays two important roles in the growth process: increasing mass transport of CO2 and catalyzing cage formation at the solid-liquid interface.

In this work, we propose an extension of the Pitzer–Debye–Huckel (PDH) model for solutions containing ionic species at all concentrations. In the original PDH model, the ionic species are excluded ...

In this work, the combined COSMO-SAC and Pitzer–Debye–Huckel model is used for the prediction of the liquid–liquid equilibrium for 252 binary ionic liquid solutions, including 234 LCST (lower critical solution temperature)-negative mixtures and 18 LCST-positive mixtures. It is found that the combined model provides qualitative description of the mutual solubility of LCST-negative mixtures (AAD-x1 = 0.2451 and AAD-x2 = 0.04635) and LCST-positive mixtures (AAD-x1 = 0.3522 and AAD-x2 = 0.009418) when compared to experimental data. The model can also be used for the prediction of the LCST of such aqueous solutions. Though the ARD% of predicted lower critical solution temperatures is about 40%, the model usually provides correct relative LCST of different IL solutions. We found that the temperature derivative of the Gibbs free energy of mixing at the spinodal points provides very useful information regarding the occurrence of the critical solution behaviors. The fact that the model does not require any species...

The PR+COSMOSAC EOS has been shown to be able to utilize quantum mechanical calculation results to predict the thermodynamic properties and fluid phase equilibrium with the only input of molecular ...

Two-dimensional (2D) layered perovskites (An+1BnX3n+1, n = 1, 2, …) have recently attracted significant research interest because of their enhanced ambient stability compared to their conventional 3D counterparts. In addition to the common A-site cation engineering, using an asymmetric pseudo-halide anion, SCN-, in the anion X-site has been recently proven to be another effective approach to constitute 2D perovskites. Among these, 2D (MA)2Pb(SCN)2I2 was the most widely investigated and was considered to be a promising material owing to its good optoelectronic properties; however, its poor stability has aroused concerns in recent researches. In this study, systematical composition engineering of A2Pb(SCN)2X2 (A = FA+, MA+, Cs+ and X = Br-, I-) was conducted. Our results revealed that the linear SCN- anion dictates critical restrictions on the constituent ions of its derived 2D framework (PbX4(SCN)2), which has not yet been extensively discussed. We demonstrated that using a smaller Cs+ cation can afford a more favorable 2D structure compared with the MA+ cation. Cs2Pb(SCN)2I2 was revealed to possess improved stability and photo-response compared to (MA)2Pb(SCN)2I2. Interestingly, Cs2Pb(SCN)2I2 and (MA)2Pb(SCN)2I2 appear to possess distinct electronic band structures. This is indicated by their discrepant photoluminescence spectra, in which the former exhibits a rather intense singlet emission at room temperature in contrast with the latter, which shows a dominant emission associated with triplet or defective states. Furthermore, using a smaller Cs+ cation enables facile replacement of a smaller halide anion. A series of mixed-halide 2D Cs2Pb(SCN)2(I1-xBrx)2 (x = 0, 1/3, 1/2, 2/3, 1) with varying vivid colors was explored by both calculation and experimental efforts to corroborate the enhanced stability when the x value increases. The results revealed in this study might represent a novel discovery of an inherent trait of the 2D SCN-based perovskites and also suggest that the all-inorganic 2D Cs2Pb(SCN)2X2 perovskite system is a promising class of materials with good stability and color-tunability that deserves further exploration.

We present a method based on the two-phase thermodynamic model (2PT) to calculate the entropy and free energy of various molecular systems in two dimensions (2D) using molecular dynamics (MD) simulations. The 2PT method has been used widely to calculate absolute entropy in a variety of molecular systems in three dimensions. When applying the idea to 2D systems, we found that the fluidicity that determines the decomposition of the vibrational density of states (DoS) into a solidlike and a gaslike component needs to be revised. The solid part is treated using quantum statistics, and the gas part is treated as a hard-disk fluid. We validate this method by computing thermodynamic properties of a two-dimensional Lennard-Jones fluid over a range of densities and temperatures and find excellent agreement with these quantities computed from the equation of state. More importantly, this method allows for the calculation of the entropy and free energy of 2D systems efficiently from a single MD trajectory of less than 50 ps; therefore, it can be a new, powerful way of assessing the thermodynamic properties in 2D problems.

Molecular dynamics simulations were conducted to study the equilibrium and transport properties of methane/water two-phase systems with sodium dodecyl sulfate (SDS) at the interface. In particular, the properties were determined at different SDS packing fractions, 0%, 25%, 50%, 75%, and 100%. The calculated interfacial tension, determined from the difference of normal and transverse components of the pressure tensor, was found to decrease with increasing SDS concentration at the methane/water interface, whereas the equilibrium partition of methane in the gas and water phases remained nearly unchanged. Both of these results were in quantitative agreement with experimental observations. The presence of SDS at the interface increased the free energy barrier of methane transport through the interface. Therefore, it was found that the rate of methane transport across the interface slowed down with increasing SDS concentrations. In other words, the thermodynamic driving force was unchanged, but the kinetic barr...

The pKa of an acid is important for determining the dissociation and thermodynamic properties of solutions containing it. However, the value of pKa is typically determined at dilute limit and cannot be used to describe properties of the solution at high concentrations. In this work, we propose an approach to determine the concentration independent equilibrium constant Keq based on pKa and predicted activity coefficients. The Keq determined is applied to predict the degree of dissociation over whole concentration range for weak to strong acids. The pH of acid aqueous solution is predicted over whole concentration range, showing a good agreement with experiments. Based on this approach, we found that the vapor pressures of acid aqueous solutions strongly depend on the degree of dissociation of acids. The proposed model provides useful insights to link the macroscopic properties of acid aqueous solutions to its microscopic dissociation phenomena over the whole concentration range.

The two-phase thermodynamic (2PT) model provides an efficient route for calculating the absolute entropy values from a typical trajectory of molecular dynamic simulations. The method calculates the entropy based on the vibrational density of state (DOS), which is considered to be the superposition of contributions from a gas-like and a solid-like component. A fluidicity parameter is used to determine the fraction of the gas-like component, which is considered as a hard-sphere gas. The DOS of the hard-sphere gas was estimated using a delta memory function. Recently Desjarlais suggested to use a Gaussian memory function for better description of the gas-like DOS, in particular in the high-frequency region. However, a systematic but tedious approach involving the evaluation of moments of the DOS was required for evaluating the fluidicity. In this work, we propose a new approach to determine the fluidicity which can be easily implemented in a computer code. We validated this new approach by calculating the entropy of Lennard–Jones fluids in the gas, liquid, solid, and supercritical regions. It is found that the entropy determined from using the Gaussian memory function for the gas-like component (denoted as 2PT-GMF) is always lower than that determined from that using delta memory function (denoted as 2PT-δMF). Furthermore, 2PT-GMF is more accurate (with an absolute average relative error of 1% compared to the results from MBWR EOS) than 2PT-δMF (AARD = 2%) in the liquid and supercritical regions, whereas their performances are comparable in other regions (AARD = 1%).

Background Phase separation solvents have been developed for CO2 capture with the advantage of low regeneration energy. Understanding the mechanism of phase change driven by CO2 capture is critical toward design of phase separation solvents. Methods In this work, the molecular information of σ-profile and simulated ternary liquid–liquid equilibrium (LLE) phase diagram obtained from a predictive modeling based on COSMO-SAC method is used to investigate the phase behavior of phase separation solvents before and after CO2 absorption. Significant findings Ternary mixtures of three selected amines [2-aminoethanol (MEA), 2-(ethylamino)ethanol (EAE), 2-(butylamino)ethanol (BAE)] + water + glycol ether, with different strengths of hydrophilicity of amines, exhibit three types of partially miscible behaviors. Upon absorption of CO2, amine reacts to form hydrophilic reaction products (carbamate + protonated amine), resulting in the change of the molecular interactions and immiscible behaviors. Our study shows that amines, such as EAE, having a balanced interaction with water and glycol ether (exhibiting small immiscible region) are potential candidates for amine + water + glycol ether based phase separation solvent for CO2 capture.

The COSMO-SAC modeling approach has found wide application in science as well as in a range of industries due to its good predictive capabilities. While other models for liquid phases, as for example UNIFAC, are in general more accurate than COSMO-SAC, these models typically contain many adjustable parameters and can be limited in their applicability. In contrast, the COSMO-SAC model only contains a few universal parameters and subdivides the molecular surface area into charged segments that interact with each other. In recent years, additional improvements to the construction of the sigma profiles and evaluation of activity coefficients have been made. In this work, we present a comprehensive description of how to postprocess the results of a COSMO calculation through to the evaluation of thermodynamic properties. We also assembled a large database of COSMO files, consisting of 2261 compounds, freely available to academic and noncommercial users. We especially focus on the documentation of the implementation and provide the optimized source code in C++, wrappers in Python, and sample sigma profiles calculated from each approach, as well as tests and validation results. The misunderstandings in the literature relating to COSMO-SAC are described and corrected. The computational efficiency of the implementation is demonstrated.

In a recent work, Chen and Lin showed that the consideration of directional hydrogen bonding in the COSMO-SAC model significantly improves the description of solvation properties of the associating fluids. In their method, the direction of a hydrogen bond was determined based on VSEPR theory; however, this geometric approach does not reflect the local electronic environment of the lone pairs and cannot be applied to certain molecules such as DMSO and HF. In this work, we adopt a new scheme that determines the hydrogen bond acceptors of a molecule based on the minima in the molecular electrostatic potential (MESP). The hydrogen bonding directions thus determined result in improvements (about 5–7% for VLE) in the prediction of the COSMO-SAC model for a variety of thermodynamic properties and phase equilibria, such as vapor–liquid equilibrium (VLE), liquid–liquid equilibrium (LLE), the infinite dilution activity coefficient (IDAC), and the octanol–water partition coefficient (Kow) calculations.

The value of fine and specialty chemicals is often determined by the specific requirements in their physical and chemical properties. Therefore, it is most desirable to design the structure of chemicals to meet some targeted material properties. In the past, the design of specialty chemicals has been based largely on experience and trial-and-error. However, recent advances in computational chemistry and machine learning can offer a new path to this problem. In this presentation, we demonstrate a successful example where the structure of a chemical of specified value of octanol–water partition coefficient (Kow) can be predicted by computers. This method consists of two parts, the first being a robust method, the COSMO-SAC activity coefficient model, that predicts the activity coefficient with input of only the molecular structure. The second component of this method is a derivative-free optimization algorithm that searches in the multidimensional structure space for the desired value of Kow. In particular,...

The predictive capability of gas and liquid solubility in organic polymers is examined based on the combination of the PR+COSMOSAC equation of state (EOS) and the COSMO-SAC liquid model through three different excess Gibbs free energy based mixing rules, modified Huron-Vidal (MHV1), Wong-Sandler (WS), and self-consistent mixing rule (SCMR). Using 81 binary systems consisting of 23 gas molecules and 22 polymers (81 data points) with temperatures ranging from 298 to 461 K, it is found that WS and SCMR can provide reasonable prediction accuracy (RMSE(log10 kH) = 0.746 and 1.725, respectively) for the Henry’s law parameter in polymers, while the MHV1 mixing rule results in a much larger error (RMSE (log10 kH) = 3.118) compared to experiment. The WS and SCMR, but not MHV1, provide a converged value of Henry’s law parameter of gas in polymers as the molecular weight of the polymer increases. We further propose a modification to the SCMR (mSCMR) that results in significant improvement in the solubility predictio...

Six predictive approaches based on the Peng-Robinson (PR) equation of state (EOS), conductor-like screening model segment activity coefficient (COSMO-SAC), and mixing rules were applied to model solid-liquid-gas equilibrium for 21 binary mixtures of CO2 and an organic compound. The accuracy of these approaches in predicting equilibrium temperatures at given pressures (635 experimental data with T = 220 ∼ 413.97 K and P = 0.05 ∼ 48.35 MPa), liquid phase compositions, and liquid molar volumes was examined and compared to provide an overview on their performance. The recently developed PR + COSMO-SAC EOS was found to be most accurate, with deviations of 6.25 K in temperature, 0.071 in liquid mole fraction, and 21% in liquid molar volume. The performance of these models can be very different for the solid containing different functional groups. Nevertheless, the PR + COSMO-SAC EOS could provide useful a priori predictions with only input of experimental heat of fusion and melting temperature of the solid.

Der vorliegende Ubersichtsartikel berichtet uber Fortschritte in der molekularen Modellierung und Simulation mittels massiv-paralleler Hoch- und Hochstleistungsrechner (HPC). Im SkaSim-Projekt arbeiteten dazu Partner aus der HPC-Community mit Anwendern aus Wissenschaft und Industrie zusammen. Ziel dabei war es mittels HPC-Methoden die Vorhersage von thermodynamischen Stoffdaten in Bezug auf Effizienz, Qualitat und Zuverlassigkeit weiter zu optimieren. In diesem Zusammenhang wurden verschiedene Themen bearbeitet: Atomistische Simulation der homogenen Gasblasenbildung, Oberflachenspannung klassischer Fluide und ionischer Flussigkeiten, multikriterielle Optimierung molekularer Modelle, Weiterentwicklung der Simulationscodes ls1 mardyn und ms2, atomistische Simulation von Gastrennprozessen, molekulare Membran-Strukturgeneratoren, Transportwiderstande und gemischtypenspezifische Bewertung pradiktiver Stoffdatenmodelle.

The diffusion coefficient of methane in water plays an important role in the formation and dissociation of methane hydrate. However, most of the previous studies on the diffusion coefficient of methane in brine are performed at room temperature and low pressures, which is quite different from the formation condition of methane hydrate. In this study, we measure the diffusion coefficient of methane in pure water and brine in capillary tube at 10.3 MPa and temperature ranging from 283.15 to 308.15 K. We use the Raman spectrum to measure the ratio of C-H bound signal of methane to the O-H bound signal of water, to estimate the concentration of methane dissolves in water/brine. The Raman spectrum is collected at different time and different positions away from the liquid-gas interface. Diffusion coefficient is determined by fitting the experimental data with the concentration profiles solved from Fick’s second law and semi-infinity boundary condition. By this method, we can evaluate the diffusion coefficient at different temperatures or salinities. The diffusion coefficient of methane in water/brine increases as the temperature increases. The diffusion coefficient of methane in brine is lower than that in pure water. Molecular dynamics (MD) simulation is also performed in this study to calculate the diffusion coefficient of methane in water/brine. The MD results can successfully predict the tendency of temperature effect and adding electrolyte.

This work aims at evaluating potential direct CO2 conversion processes through systematic screening and process simulation. Fifteen direct routes converting CO2 to carbonates or carbamates, with in situ chemical dehydration using 2-cyanopyridine (2-CP) are focused. The work covers an extensive examination (and supplement) on the physical properties, selection of promising routes, process simulation, optimization, environmental, and techno-economic evaluation. Firstly, three promising routes were selected, producing dimethyl carbonate (DMC), dipropyl carbonate (DPC), and Isopropyl N-phenylcarbamate (IPPhCM), based on three criteria: azeotropic search, product selectivity and reacting conditions. Next, the corresponding processes were simulated, optimized, heat-integrated, and systematically compared with the previously-proposed diethyl carbonate (DEC) process through environmental and economic analysis. From environmental analysis, the CO2 emission rate (CO2-e, in kg/kg-product) was 0.067, 0.088, −0.040 and −0.154 for producing DMC, DPC, IPPhCM and DEC, respectively. By reducing the excess ratio used for reaction (i.e. 2-CP/alcohol or amine/alcohol), the CO2-e improved to −0.122, −0.086, and −0.117 for producing DMC, DPC and IPPhCM, respectively. Finally, the minimum required selling prices (MRSP) at 15 % internal rate of return (IRR) were determined, with the unit price of 2-CP, 2-picolinamide (2-PA), and the reactor residence time regarded as uncertainties. The MRSPs for DMC, DPC, IPPhCM and DEC are found in the range of 1.50–4.96, 2.29–4.24, 2.07–4.06 and 1.12–2.81 (all in USD/kg), respectively. Future studies exploring the commercial availability and the regeneration of 2-CP, and the feasibility of reducing the excess ratio and the reaction residence time are considered helpful.

There is a growing interest in developing CO2 capture processes based on phase separation solvents due to its much lower energy consumption compared to the reference amine process using monoethanolamine (MEA). In this work, the predictive COSMO-SAC activity coefficient model was applied to describe phase behavior for phase separation solvent composed of amine + water + glycol ether. From the calculated ternary liquid-liquid equilibrium (LLE) phase diagram, ternary mixtures of fourteen selected amines + water + glycol ether can be classified into miscible- or immiscible-type solvents. The work presented here indicates that amines having comparable affinity to water and glycol ether generally result in a smaller two-phase region and form type I phase behavior near the amine-lean region. The amines having a strong affinity to water or glycol ether show a larger two-phase region and result in type II phase behavior. Further analysis shows that KOW and σ -profile can be good indicators for the affinity of amine to water and glycol ether, which is the key factor to determine the phase behavior of investigated ternary mixtures. The feed composition and operating temperature of phase separation solvent should be judged by the interaction between solvent molecules. This study demonstrates that COSMO-SAC is a useful tool for exploiting the phase behavior of potential phase separation solvents with limited available experimental data.

We address the possible occurrence of a minimum extent of dissociation (α) of ionic liquid (IL) in IL-solvent mixtures. This phenomenon, known as the redissociation of IL, is responsible for many interesting composition-dependent properties in such mixtures. A thermodynamic model is developed to provide a semiquantitative prediction on the change of α with solvent concentration. It is found that the occurrence of minimum α coincides with the occurrence of a maximum in the mean activity coefficient of dissociated ions, indicating better solvation of free, dissociated ions both with decreasing and increasing solvent concentration. The favorable solvation of free ions is found to change from long-range ion-solvent dielectric polarization to ion-ion-pair dielectric polarization with decreasing solvent concentration. Therefore, the composition dependence of the IL solution dielectric constants, determined from that of the ion-pair and the solvent, is found to be the most important factor for the presence of redissociation in IL solutions.

Water vacancy is a defect in clathrate hydrates which facilitates gas diffusion by lowering the energy barrier for the cage hopping transfer of guest molecules. By performing molecular dynamics (MD) simulation on single phase sI CH4 and CO2 hydrates, we explore the dynamics of guest hopping and the concurrent evolution of a hydrogen bond network on the hopping sites. The inclusion of the water vacancy allows us to observe microscopic mechanisms of gas hopping in stable (i.e., away from dissociation temperature) hydrates within 100 ns simulations. Diffusion coefficients of guest gases are estimated from the obtained hopping rate, which have qualitative agreement with literature experimental data and simulation calculations (estimated CO2 diffusivities are 3.6 × 10–16 m2/s at 273 K and 1.1 × 10–15 m2/s at 288 K). The single water vacancy defect causes on average four damaged cages and propagates in the system with a diffusivity of ca. 10–12 m2/s. When the defect locates between an occupied and an unoccupied...

In this work, we investigated the prediction of solubility (xd) of drug molecules in single- and mixed-ionic liquid (IL) solutions using the COSMO-SAC activity coefficient model. In particular, the effect of dissociation of IL on solubility is examined. The prediction accuracy is found to be 91% in xd (root-mean-square deviation in ln xd is 0.65) for a total of 442 data points with solubility ranging from 0.93 to 2.84 × 10−4 (mole fraction) and temperature ranging from 248.92 K to 488.3 K. The solubility of drug is found not sensitive to the treatment of dissociation of IL in the calculations. The method is used to determine the solubility of paracetamol in 2,624 single IL made from combination of 82 cations and 32 anions. The solubility of paracetamol can vary by 4 orders of magnitude in different ILs, indicating that this is a powerful method for screening for solvents with desired solubility power. The solubility of a drug in binary IL solution can be significantly higher or lower than those in pure IL components. For the 3,441,376 binary IL mixtures, about 8% of the mixtures exhibit higher solubility for paracetamol and 6% exhibit lower solubility. Our results indicate that mixing ILs can be a viable approach for tuning drug solubility. This article is protected by copyright. All rights reserved.

The activity coefficient of a chemical in a mixture is important in understanding the thermodynamic properties and non-ideality of the mixture. The COSMO-SAC model based on the result of quantum mechanical implicit solvation calculations has been shown to provide reliable predictions of activity coefficients for mixed fluids. However, it is found that the prediction accuracy is in general inferior for associating fluids. Existing methods for describing the hydrogen-bonding interaction consider the strength of the interaction based only on the polarity of the screening charges, neglecting the fact that the formation of hydrogen bonds requires a specific orientation between the donor and acceptor pairs. In this work, we propose a new approach that takes into account the spatial orientational constraints in hydrogen bonds. Based on the Valence Shell Electron Pair Repulsion (VSEPR) theory, the molecular surfaces associated with the formation of hydrogen bonds are limited to those in the projection of the lone pair electrons of hydrogen bond acceptors, in addition to the polarity of the surface screening charges. Our results show that this new directional hydrogen bond approach, denoted as the COSMO-SAC(DHB) model, requires fewer universal parameters and is significantly more accurate and reliable compared to previous models for a variety of properties, including vapor-liquid equilibria (VLE), infinite dilution activity coefficient (IDAC) and water-octanol partition coefficient (Kow).

A new molecular data structure and molecular structure operation algorithms are proposed for general purpose molecular design. The data structure allows for a variety of molecular operations for creating new molecules. Two types of molecular operations were developed, unimolecular and bimolecular operations. In unimolecular operations, a child molecule can be created from a parent via addition of a functional group, deletion of a fragment, mutation of an atom, etc. In bimolecular operations, children molecules are generated from two parent molecules through combination or crossover (hybridization). These molecular operations are essential for the creation and modification of molecules for the purpose of molecular design. The data structure is capable of representing linear, branched, multifunctional, and multivalent compounds. Algorithms are developed for deriving the molecular data structure of a molecule from its atomic coordinates and vice versa. We show that this new molecular data structure and the developed algorithms, referred to as Molecular Assembling and Representation Suite, allow one to generate a comprehensive library of new molecules via performing every possible molecular structure modification.