Kaxiras Efthimios Tim Reasearch Group Multiscale Modeling Materials


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Welcome to the Research Group of Professor Efthimios Kaxiras.
An overview of current research topics is given further down.
There are two central themes in our current research: the development of multiscale methods to couple disparate spatial and temporal scales for the study of complex physical phenomena, and the application of such methods to problems related to energy conversion and energy storage systems.

Research Highlight: The following two movies show the process of electron-hole separation after excitation by light absorption in a hybrid photovoltaic device called "dye sensitized solar cell" (DSSC), also known as "Graetzel cell" from its inventor Michael Graetzel. The movie on the left shows the electron wavefunction (green cloud) on an organic dye, that is quickly injected into the titanium-dioxide nanowire substrate (represented by the blue and red spheres for titanium and oxygen atoms) on which the dye is anchored; the movie on the right shows the hole wavefunction (yellow cloud) that is stuck to the organic dye. The electron-hole separation is crucial for the efficient operation of the device. For more details see relevant papers under "Nanostructures".

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The following diagram summarizes active research areas, indicated by overlaping colored circles, and the general areas of their application.

Briefly, the topics in each research area are:
1 - Mechanochemistry: the effects of chemical impurities on the large-scale mechanical behavior of solids.
2 - Surface science: atomic-scale structure of solid surfaces and its effect on properties of electronic devices and heterogeneous catalysis.
3 - Nanostructures: structure and properties of low-dimensional, nano-scale systems, including carbon nanotubes, graphene nanoflakes and nanowires.
4 - Biomolecules: properties of DNA and its interaction with solid surfaces and nanostructures; other molecules with important biological functions, such as melanin and flavonoids.

Multiscale Hemodynamics: From 2007 to 2010 we collaborated with Italian scientists Simone Melchionna, Sauro Succi, Massimo Bernaschi and Mauro Bisson (Consiglio Nazionale delle Ricerche, Rome) and our Harvard Medical School colleagues Charles L. Feldman, Peter H. Stone and Frank J. Rybicki (Brigham and Women's Hospital), to simulate blood flow in the heart arteries. The culmination of this project was a simulation of blood flow in real arteries including red blood cell motion; this paper was a finalist for the Gordon Bell Prize at SuperComputing-10 (see a related movie from the simulation, and a video intended for general audiences).

Research Positions: For graduate and postdoctoral research positions please contact Prof. Kaxiras [kaxiras at physics.harvard.edu].
Qualified persons should send their CV and names of references. Harvard is an equal opportunity employer and encourages applications from under-represented groups such as women and minorities.

Research Topics

Hybrid photovoltaics

Graphene nanoflakes

Reactivity of Au surface

DNA-CNT interaction

Multiscale hemodynamics