Role of Electronic Correlation in the Si(100) Reconstruction: A Quantum Monte Carlo Study

Recent low-temperature scanning tunneling experiments have questioned the generally accepted picture of buckled silicon dimers as the ground state reconstruction of the Si(100) surface, undermining the ability of density functional theory to accurately describe electronic correlations at surfaces. We present quantum Monte Carlo calculations on large cluster models of the surface, and conclude that buckling remains energetically favorable even when the present-day best treatment of electronic correlation is employed. The implications for experimental interpretation are discussed.