Torsional potential of biphenyl: Ab initio calculations with the Dunning correlation consisted basis sets

Abstract

The internal rotational barrier heights of biphenyl were calculated with the Dunning correlation consisted basis sets (up to cc-pVQZ, 960 basis functions) and the electron correlation correction by the second order Mo/ller-Plesset method (MP2). Although previous Hartree–Fock (HF) and MP2 calculations showed that the internal rotational barrier height at 0° (ΔE0) was substantially larger than that at 90° (ΔE90), our MP2/cc-pVQZ//MP2/6-31G* calculations showed that ΔE0 (2.28 kcal/mol) was close to ΔE90 (2.13 kcal/mol), which agreed with the estimation from experimental measurements. The calculations of benzene dimers suggested that the dispersion interaction increased the relative stability of the coplanar conformer. The basis sets employed in the previous calculations were not large enough to evaluate the attractive dispersion interaction. The underestimation of the stabilization of the coplanar conformer by the dispersion interaction would be one of the reasons for the overestimation of ΔE0 in the previous calculations.

Adsorption of 4,4′‐biphenyl diisocyanide on gold nanoparticle surfaces investigated by surface‐enhanced Raman scattering

“…It is a matter of conjecture, however, whether the two benzene rings of BPDNC have a twisted structure on gold as found in the gaseous state. 25 Considering the almost perpendicular orientation of the adsorbate, the two benzene rings of BPDNC should not lie on the same plane. We should mention that several crystal faces are present on the nanoparticle surfaces.…”

Thermochemical Properties of Polycyclic Aromatic Hydrocarbons (PAH) from G3MP2B3 Calculations

“…[22][23][24] The MP2 calculations predict an energy barrier of 12.5 kJ/mol for the ortho and 7.7 kJ/mol for the planar configurations. Tsuzuki et al 18 performed similar MP2 calculations with larger basis sets as well as other methods like MP4 (fourth-order Møller-Plesset perturbation) and CCSD(T) (coupled cluster both single and double substitutions with perturbative estimation of the contributions of triple excitations). With these quite costly levels of theory, they were able to reproduce the energy barrier at 90°, but not the one at 0°.…”

“…This method fills the gap between the inaccurate B3LYP and the very expensive CC methods and has been used widely for computations of torsional potentials of substituted aromatic hydrocarbons. [16][17][18] Both B3LYP and MP2 calculations are performed using the Dunning correlation consistent basis sets. In the scope of the present work, using the second-order perturbation theory (MP2) with the first Dunning basis set (cc-pVDZ) was found to be a good compromise between accuracy and cost.…”

Theoretical investigation of the structure and the electron-vibrational dynamics of 9,9′-spirobifluorene

“…The molecular rigidity due to spiro-linkage suppresses non-radiative deactivation pathways (leading to high photoluminescence quantum yields) and increases the effective p electron conjugation [16]. On the other hand, the remaining rotational degrees of freedom keep the Stokes shift large, corresponding to geometrical relaxation of the lowest excited singlet state [17,18].…”