Theoretical Modeling of Fluorescence Properties in Biological Systems
EMSL Project ID
30992
Abstract
In this project high level ab initio methods will be used to study photophysical properties of nucleic acid bases and their fluorescent analogs. The natural nucleobases have ultrashort excited state lifetimes and very short quantum yields for fluorescence. Small modifications in their structure renders them fluorescent. We seek to understand these effects by calculating potential energy surfaces (PESs) of the excited states of these systems and comparing their features. Conical intersections are of particular interest since they facilitate radiationless decay and fluorescence quenching. Multireference configuration interaction as implemented in the COLUMBUS suite of programs and completely renormalized equation-of-motion coupled cluster techniques as implemented in NWChem will be used to obtain accurate energies on PESs. Due to a large number of single point calculations that need to be performed in order to obtain a reliable characterization of the excited-state PESs for a wide variety of internuclear geometries, the use of highly scalable software is of paramount importance. Both of the computational packages that will be used satisfy this requirement. Monomers and pi-stacked dimers will be considered. A QM/MM approach will also be used to account for solvent and other environmental effects. Project Details
Project type
Capability Research
Start Date
2008-10-03
End Date
2009-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Kozak CR, KA Kistler, Z Lu, and S Matsika. 2010. "Excited-State Energies and Electronic Couplings of DNA Base Dimers." Journal of Physical Chemistry B 114(4):1674-1683. doi:10.1021/jp9072697