Accessing the Accuracy of Density Functional Theory through Structure and Dynamics of the Water–Air Interface

Abstract

Density functional theory-based molecular dynamics simulations are increasingly being used for simulating aqueous interfaces. Nonetheless, the choice of the appropriate density functional, critically affecting the outcome of the simulation, has remained arbitrary. Here, we assess the performance of various exchange–correlation (XC) functionals, based on the metrics relevant to sum-frequency generation spectroscopy. The structure and dynamics of water at the water–air interface are governed by heterogeneous intermolecular interactions, thereby providing a critical benchmark for XC functionals. We find that the XC functionals constrained by exact functional conditions (revPBE and revPBE0) with the dispersion correction show excellent performance. The poor performance of the empirically optimized density functional (M06-L) indicates the importance of satisfying the exact functional condition. Understanding the performance of different XC functionals can aid in resolving the controversial interpretation of the interfacial water structure and direct the design of novel, improved XC functionals better suited to describing the heterogeneous interactions in condensed phases.

Self-interaction error overbinds water clusters but cancels in structural energy differences

“…This article helps to explain how the SCAN functional can significantly overbind the hydrogen bond between two water molecules and still accurately predict the small energy differences between competing hydrogen bond networks in water hexamers (29), bulk liquid water (22,30,69,70), and liquid water at an interface (71)(72)(73). The correct features of SCAN that improve structural energy differences are almost independent of its SIE that produces the overbinding.…”

Decoding the molecular water structure at complex interfaces through surface-specific spectroscopy of the water bending mode

“…We used the AIMD trajectories of the D 2 O-air interface obtained in our previous work. 59 In short, we used the B3LYP-D3(0) and revPBE0-D3(0) levels of theory for the AIMD simulations. The D-O-D bend frequencies were converted to the H-O-H bend frequencies by using a factor of 1/0.735.…”

Hydrogen bond dynamics of interfacial water molecules revealed from two-dimensional vibrational sum-frequency generation spectroscopy

“…Furthermore, the structure and dynamics of the interfacial water molecules have been extensively investigated using molecular simulations [17][18][19][20][21] . In computational studies, within the linear response regime, the second-order susceptibility ( χ ijk ) is calculated using the dipole-polarizability ( µ − α ) cross-correlation function [22][23][24][25][26] .…”