Abstract of the talk// Large-scale simulations of molecular liquids require an accurate description of intermolecular interactions. Jürg developed an electronic structure framework that combines the accuracy of the Harris functional approach with the computational efficiency of approximately linear-scaling density functional theory (DFT). The non-variational nature of the Harris functional has been addressed by constructing a Lagrangian energy functional, which restores the variational condition by imposing stationarity with respect to the reference density. The associated linear response equations can be solved with linear-scaling efficiency in an atomic orbital based scheme. 

Embedded in the CP2K program package, the method is designed to enable ab initio molecular dynamics simulations of molecular solutions for system sizes of several thousand atoms. Available subsystem DFT methods may be used to provide the reference density required for the energy correction at near linear-scaling efficiency. As an example of production applications, Jürg and his team applied the method to molecular dynamics simulations of the binary mixtures cyclohexane-methanol and toluene-methanol, performed within the isobaric-isothermal ensemble, to investigate the hydrogen bonding network in these non-ideal mixtures. 

The same computational framework can also be used in the context of density-corrected DFT and can be combined with machine learning approaches.