Ab Initio Calculations on Heteroatomic Systems Using Density Functional Theory and Diffuse Basis Functions

Generation and Identification of Ionic and Neutral Dithioformic Acid [HC(S)SH]•+/o, Dimercaptocarbene [HSCSH]•+/o, and Dithiirane [H2C(S2)]•+/o: a Neutralization−Reionization Mass Spectrometry and Theoretical Study

“…Dioxirane ( g ) and carbonyl oxide ( h ) have eluded observation in the gas phase. Though there are several calculations reported in the literature on g and h , − , we could not find these at the B3LYP/6-31G** level. Contrasting relative energies calculated for the oxygen and sulfur analogues point to the difficulties involved in obtaining g and h in the gas phase.…”

p-Phenylenebismethylene: Characterization, Calculation, and Conversion to a Conjugated Bis-Carbonyloxide

“…B3LYP/6-31G** calculations on bis-carbonyloxide 7 gave a less satisfactory fit to the experimental spectra. Following the lead of Warner, however, we found that addition of diffuse functions (B3LYP/6-31+G**) significantly improved the agreement between experiment and theory . The simpler 6-31G** basis set sufficed to confirm the assignment of bis-dioxirane 8 based on IR spectra…”

A Computational Study of the Electronic Properties of Heterocirculenes: Oxiflowers and Sulflowers

“…A frontier orbital energy gap is an important value to study the charge transport of the structures and the related physical properties in solid and liquid states. , In this study, for each molecule in data sets, the 3D structures are fully optimized at the level of theory B3LYP/6-31+G­(d,p) DFT method , by using the GAUSSIAN 09 program . The B3LYP method is chosen for its rather accurate predictions in calculating the HOMO-LUMO gap of heterocycles, especially thiophene and furan derivatives in dye compounds. , Since these classes contain conjugated systems such as thiophene- and furan-based materials (lone pairs), the basis set is often added to diffuse functions to calculate more accurately the optimization and polarizability properties. ,, …”

“…22,24 Since these classes contain conjugated systems such as thiophene-and furan-based materials (lone pairs), the basis set is often added to diffuse functions to calculate more accurately the optimization and polarizability properties. 5,25,26 In this study, there are two sets of molecules formed. First, a ring-annulated set is composed by annulated oligo-furans and oligo-thiophenes (C 2+2m X m H 4 ; X: O and S; m = 1−5); this set is used to re-assess the possibility of the basis set of B3LYP/6-31+G(d,p) for collecting the strain energy parameter, compared to the PBE method in a previous study.…”