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In this paper, the effect of the simultaneous rotation of two different groups, hydroxyl (OH) and hydroxymethyl (CH2OH) groups, on the basic properties of Glycerol are comprehensively studied. Relative energies are reported at the HF/ aug-cc-pVDZ, b3lyp/ aug-cc-pVDZ levels with corrections for zero-point vibrational energies. Structural parameters, Electric Dipole Moment and HOMO-LUMO energy gap of the identified conformers are also tabled. An inverse correlation between the relative energy and HOMO-LUMO energy gap is seen.

The potential energy surface (PES) of aniline was comprehensively investigated at different levels in this paper. The stable conformer of aniline has CS point group while the transition states possess CS and C2V symmetries. The computed transition states of aniline are highly dependent on the level of the computations including Hartree-Fock, Density functional and Moller–Plesset perturbation theories. The electric dipole moment of the molecule varies by the rotation of the amino group with respect to the phenyl plane, while in the range of 60–120 degrees, the changes of the dipole moment is not noticeable.

A comprehensive study of the He (I) ultra-violet photoelectron spectra of fluorene, carbazole and dibenzofuran is presented with the aid of one-particle Green’s Function calculations employing the outer-valence Green’s Function (OVGF) approach and the third-order algebraic diagrammatic construction [ADC(3)] scheme, along with Dunning’s correlation consistent basis sets of double and triple zeta quality (cc-pVDZ, cc-pVTZ). Extrapolations of the ADC(3) results for the outermost one-electron π-ionization energies to the cc-pVTZ basis set enable theoretical insights into He (I) measurements within ∼0.15 eV accuracy, up to the σ-ionization onset. The lower ionization energy of carbazole is the combined result of mesomeric and electronic relaxation effects. OVGF/cc-pVDZ or OVGF/cc-pVTZ pole strengths smaller than 0.85 systematically corroborate a breakdown of the orbital picture of ionization at the ADC(3) level. Comparison is made with calculations of the lowest doublet–doublet excitation energies of the radical cation of fluorene, by means of time-dependent density functional theory (TDDFT).

The results of experimental studies of the valence electronic structure of tetrahydrofuran employing He I photoelectron spectroscopy as well as Electron Momentum Spectroscopy (EMS) have been reinterpreted on the basis of Molecular Dynamical simulations employing the classical MM3 force field and large-scale quantum mechanical simulations employing Born-Oppenheimer Molecular Dynamics in conjunction with the dispersion corrected ωB97XD exchange-correlation functional. Analysis of the produced atomic trajectories demonstrates the importance of thermal deviations from the lowest energy path for pseudorotation, in the form of considerable variations of the ring-puckering amplitude. These deviations are found to have a significant influence on several outer-valence electron momentum distributions, as well as on the He I photoelectron spectrum.