On the origin of spurious errors in many-body expansion for water cluster

Abstract

Abstract: Many-body expansion (MBE) has been carried out to investigate two- to five-body energy terms and their contributions to the interaction energy (IE) of (H 2O) 15 cluster. We have observed that the erroneous contribution of many-body terms on IE originated from cheaper convergence thresholds set as default in popular quantum mechanics packages. The propagation of errors from smaller to higher-body terms, due to the combinatorial nature of MBE, is also observed. GRAPHICAL ABSTRACT: Synopsis This study makes an attempt to investigate the effect of convergence criteria on two- to five-body energy terms and their contributions to the interaction energy of (H 2O) 15 cluster. The erroneous results of many-body terms originated from cheaper convergence thresholds set as default criteria. [Figure not available: see fulltext.].