Gaussian basis sets for use in correlated molecular calculations. V. Core-valence basis sets for boron through neon

Abstract

The correlation-consistent polarized valence basis sets ͑cc-pVXZ͒ for the atoms boron through neon have been extended to treat core and core-valence correlation effects. Basis functions were added to the existing cc-pVXZ sets to form correlation-consistent polarized core-valence sets ͑cc-pCVXZ͒ in the usual pattern: Double zeta added (1s1 p), triple zeta added (2s2 p1d), quadruple zeta added (3s3p2d1 f), and quintuple zeta added (4s4 p3d2 f 1g). The exponents of the core functions were determined by minimizing the difference between all-electron and valence-only correlation energies obtained from HFϩ1ϩ2 calculations on the ground states of the atoms. With the cc-pCVXZ sets, core, core-valence, and valence correlation energies all converge exponentially toward apparent complete basis set ͑CBS͒ limits, as do the corresponding all-electron singles and doubles CI energies. Several test applications of the new sets are presented: The first two ionization potentials of boron, the 3 P-5 S separation in carbon, and the X 3 B 1-ã 1 A 1 state separation in CH 2. As expected, correlation effects involving the core electrons of the first row atoms, B-Ne, are small but must be included if high accuracy is required.

Rate Constant and Branching Fraction for the NH2 + NO2 Reaction

“…The core−valence corrections employ the cc-pCVnZ basis sets of Dunning and Woon. 48 The relativistic corrections were obtained with the Douglas−Kroll Hamiltonian. 49 The present high level (HL) method has two sigma uncertainties for heat of formation values on the order of 0.3 kcal/mol (in comparisons with a large set of Active Thermochemical Tables (ATcT) values 50 ), while the RQCISD-(T)/CBS method has uncertainties of ∼1 kcal/mol.…”

Comparison of DFT and ab initio QM/MM methods for modelling reaction in chorismate synthase

“…MP2/aVDZ//B3LYP/6-31G(d)/CHARMM27 and SCS-MP2/aVDZ//B3LYP/6-31G(d)/CHARMM27 levels calculations), using the Molpro program [30]. The acronym aVDZ indicates that the aug-cc-pVDZ basis set was used for all atoms [34,35]. The MM partial charges of protein and water molecules were taken into account as the environment, i.e.…”

The role of metal ions in X-ray-induced photochemistry

“…For typical metals the first step is Auger decay during which electrons with characteristic energies are emitted by the metal species which in turn accumulates a positive charge. The emitted Auger electrons propagate through the system causing secondary ionisations and resulting in damaging lesions [10]. It is clear by now that in a biological medium further damaging relaxation processes are present.…”

“…We expect the Auger decay to be accompanied and followed by ultrafast electronic decay processes involving the neighbouring molecules [11]. of Mg 4+ accept an electron from a water neighbour, transferring the excess energy either to the same water molecule (ETMD(2) process) or to a different one (ETMD(3) process).…”