Welcome to the February 2009 issue. In this issue, we will discuss the use of finite elements (FEs) in quantum mechanics, with specific focus on the quantum-mechanical problem that arises in crystalline solids. We will consider the electronic structure theory based on the Kohn-Sham equations of density functional theory (KS-DFT): in real-space, Schrödinger and Poisson equations are solved in a parallelepiped unit cell with Bloch-periodic and periodic boundary conditions, respectively. The planewave pseudopotential approach is the method of choice in such quantum-mechanical simulations, but there has been growing interest in recent years on the use of various real-space mesh approaches, of which finite elements are gaining increasing prominence.

Defects in solids have been studied by the mechanics community for over five decades, some of the earliest works on this topic dating back to Eshelby. Yet, they still remain interesting, challenging, and often spring surprises—one example being the observed hardening behavior in surface dominated structures (as discussed in past journal club themes by Wei Cai and Julia Greer). In this journal theme, I wish to concentrate on the underlying physics behind defect behavior and motivate the need to combine quantum mechanical and mechanics descriptions of materials behavior. Through this discussion, I hope to bring forth: (i) The need to bridge mechanics with quantum mechanics; (ii) The challenges in quantum mechanical calculations; (iii) How the mechanics community can have a great impact.

Update: The position has been filled; thanks to all who responded.

A post-doctoral position is immediately available at UC Davis. The individual will work on a joint project led by myself and John Pask at LLNL on the development and application of a new finite-element based approach for large-scale quantum mechanical materials calculations.

Since the early 1990s, when quantum dots and quantum wires began to attract the attention of physicists, and when carbon nanotubes were discovered, mechanics related issues have begun to emerge as important in understanding properties of nanostructures.  These structures were first considered useful mostly for their electronic or optical applications, yet deformation has been seen to play an important role in their functional characteristics.  Advances in modeling also have begun to link electronic structure with mechanical properties of materials at larger length scales, particularly when microstructural or crystallographic effects influence bulk behavior.