Accurate thermochemistry for molecules containing heavy p-block elements using local explicitly correlated ab initio methods

点击翻译按钮获取中文摘要

Over the last years it has been demonstrated that accurate ab initio methods can predict thermochemical data with an uncertainty of 1-4 kJ/mol, which is often more accurate than experimental values. However, so far this is restricted to very small molecules containing first and second row atoms only. The aim of the present proposal is to extend this methodology to the remainder of the heavier p-block elements and larger molecules. The novel aspects of this work are fourfold: (i) newly developed explicitly correlated methods (MP2-F12 and CCSD(T)-F12) will be utilitized to minimize the substantial errors that can arise from the slow convergence of the 1-particle basis sets. (ii) Scalar and spin-orbit relativistic effects, which are of crucial importance in these systems, will be recovered using carefully benchmarked relativistic effective core potentials (ECPs). New systematically convergent basis sets for F12 methods in conjunction with ECPs will be developed as part of the work. (iii) Local correlation methods will be used for larger systems. (iv) Analytical energy gradients will be implemented for MP2-F12 and CCSD(T)-F12 methods.