Jelaine Cunanan (Dominican University of California, Chemistry), Holden Smith, Adam Bruner, Dr. Kenneth LopataLSU Chemistry/Center for Computation & Technology

References: Acknowledgments: This materialis basedupon worksupportedbytheNationalScienceFoundationunderawardOCI-1560410 withadditional supportfromtheCenterforComputation&TechnologyatLouisianaState University.AdditionalresearchguidancethroughouttheREUwasprovidedbyAlexMeyer.

Donghyun Lee,Loren Greenman,Mohan Sarovar,andK. Birgitta Whaley, Ab InitioCalculationofMolecularAggregationEffects:ACoumarin-343CaseStudy, TheJournalofPhysical ChemistryA 2013 117 (43),11072-11085, DOI:10.1021/jp405152h

Oxtoby,DavidW.,H.P. Gillis,andAlan Campion. Principles of Modern Chemistry. Belmont,CA:Thomson Brooks/Cole,2007. Print.M. Valiev,E.J. Bylaska,N. Govind,K.Kowalski,T.P. Straatsma,H.J.J.vanDam,D.Wang,J. Nieplocha,E.Apra,T.L. Windus,W.A.deJong,"NWChem:acomprehensiveand

scalable open-sourcesolutionforlargescalemolecularsimulations” Comput.Phys.Commun.181,1477(2010)

.

-- SimplifiedHamiltonianfora2 levelSystemEquation

Time-DependentHamiltonian&SchrodingerEquationCombined

ThisshowsthechangeofpopulationbetweentheHOMO-LUMOwhenexcitedbyaphotonovertime.(time-step:t=10 6 )

∆E

LUMO

HOMO Popu

latio

n(percentage)

ChangeinElectronPopulation

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- -

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Coupled Plasmon/Molecule before Subtraction

-40000

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Coupled Dynamics of Plasmon/Molecule after Subtraction

Plasmons: Collective e- oscillations

• Large size of nanoparticles, O(106) preclude quantum description and allows for classical modeling of optical response via Maxwell's Equations:

Finite-Difference Time-Domain:

• The FDTD method uses central differences to approximate the space and time partial derivatives.

Staggered Nature of space and time grids in FDTD

Preliminary Results:

Preliminary Results:

Conclusion

Objectives:

Snapshots of Time Dependent Electric Field for Gold NanoparticleConvergence of grid spacing for a 30nm Gold Nanoparticle FDTD Simulation

Preliminary Results:Abstract:Recently, there has been great interest in formulating a quantum-classical approach,merging Maxwell's finite difference time domain (FDTD) with the time-dependentSchrodinger equations for describing the near-field dynamics and coupled dynamics of molecules, such as light harvesting dyes adsorbed to the surface of plasmonic nano-structures. This novel quantum/classical hybrid model will combine real-time time-dependentdensity functional theory (RT-TDDFT) and FDTD to describe these dynamics.

• Create a model to describe the optical properites of a molecular dye adsorbed to the surface of a gold nanoparticle.

A nonzero subtraction indicates interaction between the gold nanoparticle and dye molecule due to energy transfer.

Quantum/Classical Modeling of Gold Nanoparticle/DyeCombined Systems

Absorption spectrum of a single malachite green molecule

MalachiteGreen

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Molecule Only

Absorption spectrum of a single malachite greenmolecule on the surface of a gold nanoparticle.

Difference in absorbance between the plasmon only, molecule only, and plasmon/molecule

simulations.

Field enhancement of two molecules

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Classical Electrodynamics

Introduction Quantum Mechanics

Coupled Classical/Quantum Dynamics