Transition state geometry prediction using molecular group contributions.

نویسندگان

Pierre L Bhoorasingh

Richard H West

چکیده

Detailed kinetic models to aid the understanding of complex chemical systems require many thousands of reaction rate coefficients, most of which are estimated, some quite approximately and with unknown uncertainties. This motivates the development of high-throughput methods to determine rate coefficients via transition state theory calculations, which requires the automatic prediction of transition state (TS) geometries. We demonstrate a novel approach to predict TS geometries using a group-additive method. Distances between reactive atoms at the TS are estimated using molecular group values, with the 3D geometry of the TS being constructed by distance geometry. The estimate is then optimized using electronic structure theory and validated using intrinsic reaction coordinate calculations, completing the fully automatic algorithm to locate TS geometries. The methods were tested using a diisopropyl ketone combustion model containing 1393 hydrogen abstraction reactions, of which transition states were found for 907 over two iterations of the algorithm. With sufficient training data, molecular group contributions were shown to successfully predict the reaction center distances of transition states with root-mean-squared errors of only 0.04 Å.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

An Ab Initio SCF-MO Study of Conformational Properties of Cyclodeca-1,2,3-triene

Ab initio calculation at HF/6-31G* level of theory for geometry optimization and MP2/6-31G*//HF/6-31G* for a single point total energy calculation are reported for the important energyminimumconformations and transition-state geometries of of cyclodeca-1,2,3-triene (1). The mostfavorable conformation of 1 is a unsymmetrical twist-chair (1-TC) structure. Degenerateinterconversion of 1-TC with it...

متن کامل

Prediction of Vapor-Liquid Equilibria Using CEOS /GE Models

The present study investigates the use of different GE mixing rules in cubic equations of state for prediction of phase behavior of multicomponent hydrocarbon systems. To predict VLE data in multicomponent symmetric and asymmetric mixtures such as systems that contain light gases (nitrogen, carbon dioxide, etc.) and heavy hydrocarbons, the SRK equation of state has been combined with excess Gib...

متن کامل

Polymer Property Modelling using Grid Technology for Design of Structured Products

Development of group contribution plus models, for the prediction of polymer properties from the drawn chemical structure, which can be later used in computer aided molecular design (CAMD) for predicting the polymer structure from the given set of target properties is the goal of this work. In general, property prediction for a given polymer structure using group contribution models require tha...

متن کامل

Automatic Transition State Searches for On-The-Fly Kinetic Calculations

Computing advances have enabled rule-based automatic generation of kinetic models of large reaction networks to replace the laborious and fallible manual methods. We propose an automatic transition state generation procedure as the first step to calculate important unknown reaction rates for the automatic Reaction Mechanism Generator (RMG). Currently in RMG, thermodynamic and kinetic parameters...

متن کامل