Real-time, local basis-set implementation of time-dependent density functional theory for excited state dynamics
Sheng Meng1, Efthimios Kaxiras
1Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA. shmeng@deas.harvard.edu
The Journal of Chemical Physics
|August 14, 2008
Summary
We developed a new method for accurate, large-scale excited state dynamics simulations using time-dependent density functional theory (DFT). This approach enables realistic modeling of molecular behavior for complex systems.
Area of Science:
- Computational Chemistry
- Quantum Mechanics
- Materials Science
Background:
- Accurate simulation of excited state dynamics is crucial for understanding photochemical processes.
- Existing methods face challenges in scalability and accuracy for complex systems.
Purpose of the Study:
- To present a novel, scalable, and accurate method for simulating excited state dynamics.
- To implement this method within the SIESTA framework for practical applications.
Main Methods:
- Utilizing a local atomic basis-set representation.
- Employing real-time propagation of excited state wave functions.
- Integration into the SIESTA (Density Functional Theory) package.
Main Results:
- Demonstrated the method's potential for accurate excited state dynamics simulations.
- Successfully applied the method to small and medium-sized molecules (H2, CO, O3, indolequinone).
- Validated the approach for large-scale simulations.
Conclusions:
- The developed method offers a robust tool for excited state dynamics.
- It is readily applicable to complex systems like nanostructures and biomolecules.
- Enhances the capabilities of time-dependent DFT for dynamic simulations.
More Related Videos
Related Concept Videos
01:12Fermi Level Dynamics
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
01:23Equilibrium Conditions for a Particle
When an object is in equilibrium, it is either at rest or moving with a constant velocity. There are two types of equilibrium: static and dynamic. Static equilibrium occurs when an object is at rest, while dynamic equilibrium occurs when an object is moving with a constant velocity. In both cases, there must be a balance of forces acting on the object.
To understand the concept of equilibrium, let us first consider the forces acting on an object. When different forces act on an object, they can...
To understand the concept of equilibrium, let us first consider the forces acting on an object. When different forces act on an object, they can...
01:26Reaction Mechanisms: The Steady-State Approximation
The steady-state approximation, also referred to as the quasi-steady-state approximation to differentiate it from a true steady state, is a widely used method for simplifying calculations in complex reaction mechanisms. This approach is particularly useful when dealing with multi-step reactions that involve reverse reactions or several steps, which can significantly increase mathematical complexity and make the reactions nearly unsolvable analytically.The steady-state approximation operates on...
02:39The Integrated Rate Law: The Dependence of Concentration on Time
While the differential rate law relates the rate and concentrations of reactants, a second form of rate law called the integrated rate law relates concentrations of reactants and time. Integrated rate laws can be used to determine the amount of reactant or product present after a period of time or to estimate the time required for a reaction to proceed to a certain extent. For example, an integrated rate law helps determine the length of time a radioactive material must be stored for its...
01:26The Van der Waals Equation
The ideal gas law is based on two simplifying assumptions: first, that there are no intermolecular attractions between gas molecules, and second, that the volume occupied by the molecules themselves is negligible compared with the volume of the container. However, these assumptions don't hold up under all conditions - specifically, at high pressures and low temperatures, as gas tends to deviate from ideal gas behavior.The van der Waals equation is an enhanced version of the ideal gas law,...
01:10Van der Waals Equation
The ideal gas law is an approximation that works well at high temperatures and low pressures. The van der Waals equation of state (named after the Dutch physicist Johannes van der Waals, 1837−1923) improves it by considering two factors.
First, the attractive forces between molecules, which are stronger at higher densities and reduce the pressure, are considered by adding to the pressure a term equal to the square of the molar density multiplied by a positive coefficient a. Second, the volume...
First, the attractive forces between molecules, which are stronger at higher densities and reduce the pressure, are considered by adding to the pressure a term equal to the square of the molar density multiplied by a positive coefficient a. Second, the volume...