Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Ahren Jasper Project Name: KTP Division: CSE Project title: Temperature- and Pressure-Dependent Kinetics Associated funding: DOE BES Other Systems: Chemistry's Blues cores b431-b460 Chemistry's linux 1300 core cluster "Linus" Science: Quantitative predictions of gas phase chemical dynamics and kinetics can be made using a combination of classical trajectories (molecular dynamics), transition state theory, and master equation calculations. A comprehensive suite of codes and methods for predicting gas phase dynamics and kinetics are being developed in CSE’s Gas Phase Chemical Dynamics Group. The present project focuses on a single aspect of these calculations: the use of classical trajectories to predict collisional energy transfer rates and efficiencies, which are key fundamental information for predicting pressure dependence. In past work we have studied several test case species, such as methane and vinyl radical. Here we are developing strategies to automate our approaches and to treat larger species, such as the esters that appear as components of biodiesels in gas phase combustion. This work requires: (1) the development of automated and validated strategies for fitting full-dimensional pot ential energy surfaces, and (2) trajectory calculations using these potentials to compute energy transfer properties. Project description: We will continue our work where we (1) fit full-dimensional potential surfaces and (2) run trajectories to calculate energy transfer. Step (1) involves our automated parallel sampling code developed in the last year using these resources. Briefly, the intermolecular potential (which has a dimensionality of 3, 5, or 6 for atomic, diatomic, and polyatomic baths, respectively) is sampled using commercial quantum chemistry (QC) programs (principally Molpro). Flexibility is provided to optimize (a) the choice of QC method and (b) sampling point placement. We will continue to optimize and broaden the applicability of our sampling strategies in the next year. For large molecules, sampling will be expensive, requiring ~2000 5-hour QC calculations. The subsequent cost of the fitting is negligible relative to the cost of sampling. Step (2) involves using our parallel trajectory code DiNT to run energy transfer trajectories. 10,000 independent trajectories are required to characterize energy transfer for each system of interest, with each trajectory taking 1-60 minutes, depending on the size of the system. We have previously considered medium sized alcohols, and next we will consider peroxides and esters. For each of these class, we will consider 12 cases for a total of 24 cases. The cost of both steps 1 and 2 will scale dramatically (in different ways) based on system size, with the largest systems considered requiring most of the computer time. For example, we estimate 10000 samples of the hexanol+Ar potential to require 5000 hrs, though we likely have to "waste" processors due to I/O limitations, thus increasing the core-hour cost by up to a factor of 3. Altogether, the quantum chemistry costs should require: 2 classes * 12 cases/class * 10,000 core-hours/case = 240,000 core-hours. In the second step, for each of the 24 cases, we will run 10,000 trajectories. These take 30 minutes, on average, for a total of 120,000 core-hours. The trajectory calculations run at near 100% parallel efficiency and scaling. Steps 1 and 2 thus require a total of 360,000 core-hours, to which we add 20% for testing and development, leading to a total request of 432,000 core-hours. In new related additional effort, we will run trajectories with the goal of characterizing the critical surface describing collisional energy transfer. Once characterized, the critical surface can be used in a generalized transition state (TST) calculation. These calculations will require approximately 60,000 core-hours. Industry partnership: None Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 492000 Q1: 123000 Q2: 123000 Q3: 123000 Q4: 123000 Justification: Storage requirements: Less than 1 TB Thank You, The LCRC Accounts System