(gc3565)Reliable Electronic Structure Prediction of Molecular Properties
EMSL Project ID
3565
Abstract
The area of environmental chemical science is dominated by issues of scaling in space and time. The goal of environmental science is to understand the current state of the environment based on our knowledge of the past and to use this information to be able to predict the future state. For example, given current practices for manufacturing, what will be their long-term environmental impact? Given potential environmental remediation strategies, what will these lead to? One does not want to use a remediation strategy that will have unforeseen consequences and introduce new environmental issues. No one wants to repeat the mistakes of the past, for example, the widespread release of chlorofluorocarbons (CFC?s) into the atmosphere. Although, we are interested in the results at large spatial and temporal scales, detailed insight into behavior at the molecular scale is key to understanding (1) how humans have impacted the environment, (2) how to remediate anthropogenic impacts on the environment, and (3) how to minimize future anthropogenic impacts. Of particular interest are reliable, accurate values for thermodynamic and kinetic properties of molecules that can be used in molecular design, in process design and in remediation models. Computational chemistry is a key technology for addressing the complex environmental cleanup problems facing the Department of Energy?s nuclear production sites, as well as the problems associated with other polluted sites in the United States and the prevention of further pollution. High accuracy from a simulation is important. A factor of 2 to 4 in catalyst efficiency may determine whether a chemical process is economically feasible or not and a factor of 4 in a rate constant at room temperature (25oC) corresponds to a change in the activation energy on the order of just less than 1 kcal/mol. Given a 50:50 starting mixture of two components, a change in the free energy, G, of less than 1.5 kcal/mol leads to a change in the equilibrium constant by a factor of 10, leading to a 90:10 mixture at 25oC. The requirement for such accuracy means that we must be able to predict thermodynamic quantities such as bond dissociation energies (De or D00) and heats of formation (Hf) to better than 1 kcal/mol and activation energies to within a few tenths of a kcal/mol ? a daunting computational task. Our goal is to develop and test the procedures needed to provide accurate predictions of such molecular properties. We will then apply such tools to the prediction of a variety of molecular properties and systems including: transition metal compounds, host/guest complexes for the design of separation systems, combustion related compounds including the propargyl potential energy surface, anionic states of solvated nucleic acid bases and amino acids related to low dose biochemistry, development of flexible, polarizable interaction potentials for water-water and ion-water interactions, high cccuracy thermochemistry for molecules including fluorinated compounds and biological molecules relevant to phosphorylation processes, novel gas phase anion including clusters, inorganic complexes, and the effects of solvation, and theoretical studies of the mechanisms of hydrolytic reactions.
Project Details
Project type
Capability Research
Start Date
2006-02-03
End Date
2006-10-25
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members