Introduction

The recent development of the Projector Augmented Wave (PAW)⁴¹ Car-Parrinello¹³² method has allowed for practical ab initio molecular dynamics simulations of transition metal complexes to be performed.^133,134 We have recently applied the method to study olefin polymerization ^123,135  and  other catalytic processes. We have found the ab initio molecular dynamics method to be a practical computational tool for studying homogenous catalysis. For  a list of  PAW aplications with molecular dynamics animations click here : PAW Applications .

What is Molecular Dynamics^137-142?

Conventional electronic structure calculations can be classified as static simulations. In these calculations the nuclear positions are optimized to locate local minima and transition states on the potential surface at the zero temperature limit. This involves, for each nuclear geometry, converging the electronic structure in order to determine the energy and forces on the nuclei. Using specialied algorithms, this information is then used to move the nuclei to a more optimal geometry. In classical molecular dynamics the nuclei are allowed to move on the potential surface according to Newton's classical laws of motion (Eqn. 1) as to simulate nuclear motion at finite (non-zero) temperatures.

        (1)

The nuclear motion generated in a molecular dynamics simulation can be utilized for a variety of purposes. Stationary points can be optimized by simply applying friction to the nuclear motion, thereby causing the system to settle into a local minimum. The motion can also be used to sample configuration space as to construct a partition function from which properties can be derived rigorously from statistical mechanics. There are also global minimization schemes which utilize molecular dynamics, such as simulated annealing.
 
 

References

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