A multitude of developments that reduce the computational cost of coupled cluster theory calculations for real materials have been explored in this project. The most notable developments include novel corrections to computed electronic correlation energies that accelerate their convergence to the thermodynamic limit and complete basis set limit, reducing the computational cost significantly. The research on finite basis set corrections was carried out by Andreas Irmler et. al. and has been published in PRL 123, 156401 (2019), JCP 151, 104107 (2019) and JCP 154, 234103 (2021). Furthermore, the work on finite size corrections for coupled cluster theory calculations of periodic systems has been published in PRX 8, 021043 (2018).
In addition to the methodological developments, several more applied research projects have been carried out and resulted in published research articles. These applied projects focus on solid-solid phase transitions, molecular adsorption on surfaces and defects. Two articles about solid-solid phase transitions have been published in PRB 98, 134108 (2018) and npj Computational Materials 5, 1-6 (2019). In these studies, we have computed enthalpy differences of different carbon and boron nitride allotropes as well as high pressure phases of hydrogen that can be used to predict temperature- pressure phase diagrams. In addition, we have performed highly accurate ab initio investigations on the interaction between single water molecules and sheets of h-BN and graphene. The obtained findings have been published in PRX 8, 021043 (2018) and JPCL 3, 358 (2019). Furthermore, an investigation of dissociative hydrogen adsorption on Silicon has been published in JCP 149, 244105 (2018). A recent work focused on the study of defects in solids and is published in PRB 108, 115125 (2023). The reported applications have clearly demonstrated the potential and high accuracy of the investigated coupled cluster methods for computational materials science. We hope that these findings will serve as useful reference values in future studies and help to improve the accuracy and efficiency of widely used methods used in computational materials science in general.
In the final phase of this project the developed computer codes used to perform massive parallel coupled cluster theory calculations have been published and made freely available at
https://github.com/cc4s(öffnet in neuem Fenster). Alongside the computer code, we have published a documentation describing the code and how it can be used.
