The mission of CSI is to develop, test, validate and apply improved multi-scale methodologies for probing Chemistry in Solution and at Interfaces. Recent developments in DFT will be tested in aqueous environments of interest for the DOE mission, such as concentrated electrolytes, phototocatalytic interfaces, electrodes for desalination, organic interfaces, and nanodevices based on biological molecules. The predictive power and the reach of molecular simulations will be enhanced with artificial intelligence methods that will bring the accuracy of quantum mechanics to the size and time scales needed to deal with correlated atomic motions in complex multicomponent fluid systems. New coarse-graining approaches based on artificial intelligence will be developed for studying phase diagrams and complex transformation paths. The study of electron transfer reactions will be brought to a new level of understanding by implementing methods for the coupled electron-nuclear dynamics beyond the Born-Oppenheimer approximation and, ultimately, with the capability of modeling field-driven reactions. To tackle the above issues we will develop new open-source codes that will run efficiently on current petascale and future exascale computer platforms and will be available to the scientific community at large. The synergy between many PIs realized at CSI will boost scientific progress and will create the optimal conditions to mentor a new generation of scientific leaders.