There is a pressing need for accurate and reliable calculation of finite temperature ground and excited state properties of nanoscale systems relevant to structural biology, hydrogen economy, environmental and material science problems. To enable such simulations with high-level ab-initio methods, such as the coupled-cluster (CC) or equation-of-motion CC approaches (EOMCC) requires not only massively parallel scalability but also a proper accounting of the dynamical fluctuations of the surrounding environment. To address this challenging task we have designed a multiscale dynamical approach that combines the accuracy and computational complexity of CC methods with the efficiency of classical molecular dynamics simulations. Our methodology is based on a seamless integration between the generic QM/MM interface, Tensor Contraction Engine module, and the classical molecular dynamics module of NWChem and offers an unprecedented ability for accurate large scale calculations of thermodynamics of ground and excited state properties. We will illustrate our approach by presenting first large scale dynamical simulation of excited state spectrum of the cytosine base in its native DNA environment using variant of the completely renormalized equation-of-motion method with singles, doubles, and non-iterative triples (CR-EOMCCSD(T)). We expect that a number of important problems in previously out of reach of high-level ab-initio methods can be addressed in the near future.