Development and application of local electron correlation methods in quantum chemistry – running

We are developing exceptionally high precision, ab initio quantum chemical methods, which are applicable to study the properties of extended, chemically relevant molecular systems. Our present, local correlation based coupled cluster [e.g., LNO-CCSD(T)] methods [Nagy, Kállay, JCP 146 214106 (2017)] are capable of providing accurate energies for molecules with a couple of hundreds of atoms close to the complete basis set (CBS) limit. We established a LNO-CCSD(T)/CBS based computational protocol with which reaction or interaction energies of such extended systems can be systematically approached within chemical accuracy (about 1 kcal/mol error). Hence our protocol provides much more reliable and predictive results compared to the frequently applied alternatives (e.g., density functional theory).
In this project we mainly employ the MRCC ( program package, which is developed in our research group and freely available for academic use. Our recent implementation is significantly more economical than the presently accessible, related alternatives regarding memory and disk requirements and single node, OpenMP parallelism. Consequently, we are capable of performing unprecedentedly large scale calculations also on the nodes of the BME supercomputer. We will further improve and assess the accuracy and efficiency of our scheme and extend our methods to the calculation of additional molecular properties, such as excitation spectra. We expect to be able to tackle systems with even 1000 atoms similarly accurately and efficiently by utilizing embedding approaches (e.g., QM/QM and QM/MM), and MPI techniques for further parallelization. Additionally, we will employ our methods to study organocatalytic reactions, enzyme systems, and spectroscopic properties of extended molecules.

Project owner:
Nagy Péter (Fizikai Kémia és Anyagtudományi Tanszék)
Web address:
Fizikai Kémia és Anyagtudományi Tanszék (VBK-FKAT)

Kele Péter (MTA TTK)
Pápai Imre (MTA TTK)
Élvonal - Kutatói kiválósági program (KKP126451)