TY - JOUR
T1 - Orbital-free density functional theory study of crystalline Li-Si alloys
AU - Xia, Junchao
AU - Carter, Emily A.
N1 - Funding Information:
We are grateful to Dr. Youqi Ke, Dr. Mohan Chen, Dr. Florian Libisch, and Dr. Ilgyou Shin for helpful discussions. We thank the Tigress High Performance Computing Center and Department of Defense HPCMP Open Research Systems for computing time. We also thank the Office of Naval Research for supporting this research.
PY - 2014/5/15
Y1 - 2014/5/15
N2 - Li-Si interactions are of great interest currently due to the potential use of silicon anodes in Li-ion batteries. As a first step toward eventual nanoscale characterization of lithiation of silicon, here we study the crystalline Li-Si alloys LiSi, Li12Si7, Li 7Si3, Li13Si4, Li 15Si4, and Li22Si5 using orbital-free density functional theory (OFDFT). The recently proposed Wang-Govind-Carter decomposition (WGCD) and Huang-Carter (HC) kinetic energy density functionals (KEDFs) are used to evaluate the electron kinetic energy. Both KEDFs predict accurate cell lattice vectors, equilibrium volumes, bulk moduli, and ground-state densities when compared to Kohn-Sham density functional theory (KSDFT) benchmarks. Elastic constants and alloy formation energies calculated with the WGCD KEDF also agree reasonably well with KSDFT. Finally, Li atom adsorption energies on the Si(100) - 2 × 1 surface are calculated as a simple initial test of the Li-Si mixing process during lithiation of silicon. The OFDFT adsorption energies again are fairly close to KSDFT values. The results in this work demonstrate the accuracy of the WGCD and HC KEDFs for materials with mixed covalent-metallic character and their considerable transferability under different chemical environments. Because of its quasilinear scaling, coupled with the level of accuracy shown here, OFDFT appears quite promising for large-scale simulation of such materials phenomena.
AB - Li-Si interactions are of great interest currently due to the potential use of silicon anodes in Li-ion batteries. As a first step toward eventual nanoscale characterization of lithiation of silicon, here we study the crystalline Li-Si alloys LiSi, Li12Si7, Li 7Si3, Li13Si4, Li 15Si4, and Li22Si5 using orbital-free density functional theory (OFDFT). The recently proposed Wang-Govind-Carter decomposition (WGCD) and Huang-Carter (HC) kinetic energy density functionals (KEDFs) are used to evaluate the electron kinetic energy. Both KEDFs predict accurate cell lattice vectors, equilibrium volumes, bulk moduli, and ground-state densities when compared to Kohn-Sham density functional theory (KSDFT) benchmarks. Elastic constants and alloy formation energies calculated with the WGCD KEDF also agree reasonably well with KSDFT. Finally, Li atom adsorption energies on the Si(100) - 2 × 1 surface are calculated as a simple initial test of the Li-Si mixing process during lithiation of silicon. The OFDFT adsorption energies again are fairly close to KSDFT values. The results in this work demonstrate the accuracy of the WGCD and HC KEDFs for materials with mixed covalent-metallic character and their considerable transferability under different chemical environments. Because of its quasilinear scaling, coupled with the level of accuracy shown here, OFDFT appears quite promising for large-scale simulation of such materials phenomena.
KW - Elastic constant
KW - Kinetic energy density functional
KW - Li-Si alloy
KW - Li-ion battery
KW - Orbital-free density functional theory
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U2 - 10.1016/j.jpowsour.2013.12.097
DO - 10.1016/j.jpowsour.2013.12.097
M3 - Article
AN - SCOPUS:84892632536
SN - 0378-7753
VL - 254
SP - 62
EP - 72
JO - Journal of Power Sources
JF - Journal of Power Sources
ER -