Generalized Gradient Approximation That Recovers the Second-Order Density-Gradient Expansion with Optimized Across-the-Board Performance

We present a new generalized, gradient approximation (GGA) to the exchange-correlation functional of density functional theory, called SOGGA11, that has better overall performance for a broad chemical database than any previously available GGA and in addition is correct to second order (SO) in the density-gradient. It provides excellent accuracy for predicting molecular bond lengths.