Abstract
A novel method for the accurate and efficient calculation of interaction energies in weakly bound complexes composed of a large number of molecules is presented. The new ALMO+RPAd method circumvents the prohibitive scaling of coupled cluster singles and doubles while still providing similar accuracy across a diverse range of weakly bound chemical systems. Linear-scaling procedures for the Fock build are given utilizing absolutely localized molecular orbitals (ALMOs), resulting in the a priori exclusion of basis set superposition errors. A bespoke data structure and algorithm using density fitting are described, leading to linear scaling for the storage and computation of the two-electron integrals. Electron correlation is included through a new, linear-scaling pairwise local random phase approximation approach, including exchange interactions, and decomposed into purely dispersive excitations (RPAxd). Collectively, these allow meaningful decomposition of the interaction energy into physically distinct contributions: electrostatic, polarization, charge transfer, and dispersion. Comparison with symmetry-adapted perturbation theory shows good qualitative agreement. Tests on various dimers and the S66 benchmark set demonstrate results within 0.5 kcal mol-1 of coupled cluster singles and doubles results. On a large cluster of water molecules, we achieve calculations involving over 3500 orbital and 12,000 auxiliary basis functions in under 10 min on a single CPU core.
Highlights
Chemistry relies on the idea that results obtained for molecules in one context are transferrable to other, similar situations
The absolutely localized molecular orbitals (ALMOs)+random phase approximation (RPA) method has been implemented in our inhouse electronic structure package,[130] which utilizes the LIBINT
Additional DF-MP2,35 CCSD,[133] CCSD(T),[133,134] and M06-2X135 calculations were performed in the MOLPRO package,[136] while DF-SAPT77,137 calculations were carried out using Psi4.138 Unless noted otherwise, all calculations use the aug-cc-pVDZ orbital basis[139−141] with the associated JKFit[127,142,143] and MP2Fit[144] density fitting sets for the Fock- and molecular orbitals (MOs)-basis integrals, respectively
Summary
Chemistry relies on the idea that results obtained for molecules in one context are transferrable to other, similar situations. The idea of a molecule implies there is an inherent locality to the underlying description While no such physical distinction truly exists, it is undeniably helpful to compartmentalize and categorize chemical systems. The latter is especially true in the case of noncovalent interactions, the ubiquitous forces underlying phenomena as diverse as geckos attaching themselves to walls,[1,2] to the cohesion of asteroids,[3] and more.[4,5] Such interactions are defined to be any stabilization weaker than would be expected for a chemical bond a definition so broad as to be insurmountably difficult to study without distinguishing further. Such a distinction is found through decomposition of the interaction into terms such as electrostatic, polarization, and dispersion;[6] the complex is typified by the predominant component
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
