Effects of charge transfer on a-SiO2 surface structure: A molecular dynamics study

AbstractColloidal CdSe nanocrystals (NCs) have shown promise in applications ranging from LED displays to medical imaging. Their unique photophysics depend sensitively on the presence or absence of surface defects. Using simulations, we show that CdSe NCs are inherently defective; even for stoichiometric NCs with perfect ligand passivation and no vacancies or defects, we still observe that the low energy spectrum is dominated by dark, surface-associated excitations, which are more numerous in larger NCs. Surface structure analysis shows that the majority of these states involve holes that are localized on two-coordinate Se atoms. As chalcogenide atoms are not passivated by any Lewis base ligand, varying the ligand should not dramatically change the number of dark states, which we confirm by simulating three passivation schemes. Our results have significant implications for understanding CdSe NC photophysics, and suggest that photochemistry and short-range photoinduced charge transfer should be much more facile than previously anticipated.

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Impact of vibronic coupling effects on light-driven charge transfer in pyrene-functionalized middle and large-sized Metalloid Gold Nanoclusters from Ehrenfest dynamics.

Physical Chemistry Chemical Physics ◽

10.1039/d1cp02890a ◽

2021 ◽

Author(s):

Adrian Dominguez-Castro ◽

Thomas Frauenheim

Keyword(s):

Molecular Dynamics ◽

Charge Transfer ◽

Density Functional ◽

Theoretical Calculations ◽

Gold Nanoclusters ◽

Tight Binding ◽

Time Dependent ◽

Effective Strategy ◽

Dynamics Simulations ◽

Dependent Density

Theoretical calculations are an effective strategy to comple- ment and understand experimental results in atomistic detail. Ehrenfest molecular dynamics simulations based on the real-time time-dependent density functional tight-binding (RT-TDDFTB) approach...

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Molecular Dynamics Study Of Si/Si3N4 Interface

MRS Proceedings ◽

10.1557/proc-446-157 ◽

1996 ◽

Vol 446 ◽

Cited By ~ 3

Author(s):

Martina E. Bachlechner ◽

Ingvar Ebbsjö ◽

Rajiv K. Kalia ◽

Priya Vashishta

Keyword(s):

Molecular Dynamics ◽

Electronic Structure ◽

Charge Transfer ◽

Md Simulations ◽

Electronic Structure Calculations ◽

Interface Structure ◽

Bond Bending ◽

Three Body ◽

Structure Calculations ◽

Weber Potential

AbstractStructural correlations at the Si(111)/Si3N4(0001) interface are studied using the molecular dynamics (MD) method. In the bulk, Si is described by the Stillinger-Weber potential and Si3N4 by an interaction potential which contains two-body (steric, Coulomb, electronic polarizabilities) and three-body (bond bending and stretching) terms. At the interface, the charge transfer from silicon to nitrogen is taken from LCAO electronic structure calculations. Using these Si, Si3N4 and interface interactions in MD simulations, the interface structure (atomic positions, bond lengths, and bond angles) is determined. Results for fracture in silicon are also presented.

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