### LANS Publications

# "Quasicontinuum-like Reduction of DFT Calculations of Nanostructures"

D. Negrut, M. Anitescu, A. El-Azab, P. Zapol

*J. Nanosci. Nanotechnol.*, vol. 8, , pp. 3729-3740. Also Preprint ANL/MCS-P1384-1206

Preprint Version: [pdf]

Density functional theory can accurately predict chemical and mechanical properties of nanostructures, although at a high computational cost. A quasicontinuum-like framework is proposed to substantially increase the size of the nanostructures accessible by simulations. It takes advantage of the near periodicity of the atomic positions in some regions of nanocrystalline materials to establish an interpolation scheme for the electronic density in the system. The electronic problem embeds interpolation and coupled cross-domain optimization techniques through a process called electronic reconstruction. For the optimization of nuclei positions, computational gains result from explicit consideration of a reduced number of representative nuclei interpolating the positions of the rest of nuclei following the quasicontinuum paradigm. Numerical tests using the Thomas-Fermi-Dirac functional demonstrate the validity of the proposed framework within the orbital-free density functional theory.