We use density functional theory (DFT) to provide energetic information for higher-level modeling activities at CAMM, such as phase field modeling. Basic physical properties like elastic constants, phonon frequencies, point defect formation energies and migration barriers, and generalized stacking fault energies¹ can be computed to high accuracy. Chemical properties such as catalytic activity² and alloy stability are being modeled. We have recently developed a k-point parallelized VASP which enables efficient calculations of dislocation core energy and Peierls stress³ in metals (bcc Mo and Fe).

We also developed an electronic-structure analysis toolkit QUAMBO, which decomposes wavefunctions obtained from planewave DFT calculations into local-orbital representation. Green’s function, projected density of states, bond order and Mulliken charge can be calculated based on the planewave results, which satisfy exact sum rules. We have also developed time-dependent DFT methods⁴ to calculate electrical and spectroscopic signatures of materials.

References Cited

1. Ogata, S., Li, J. & Yip, S. Ideal pure shear strength of aluminum and copper. Science 298, 807-811 (2002).
   
2. Qi, L., Yu, J. G. & Li, J. Coverage dependence and hydroperoxyl-mediated pathway of catalytic water formation on Pt (111) surface. J. Chem. Phys. 125, 054701 (2006).
   
3. Wang, C. Z., Li, J., Ho, K. M. & Yip, S. Undissociated screw dislocation in Si: Glide or shuffle set? Appl. Phys. Lett. 89, 051910 (2006).
   
4. Qian, X. F., Li, J., Lin, X. & Yip, S. Time-dependent density functional theory with ultrasoft pseudopotentials: Real-time electron propagation across a molecular junction. Phys. Rev. B 73, 035408 (2006).