Application of Koopmans' theorem for density functional theory to full valence-band photoemission spectroscopy modeling

Influence of phenylpropanoid units of lignin and its oxidized derivatives on the stability and βO4 binding properties: DFT and QTAIM approach

Obtaining lignin products is currently one of the great challenges, mainly because of its stable and poorly reactive structure. This work used a DFT and QTAIM approach, seeking to understand the influence of lignin structure on the reactivity and βO4 binding properties of 18 model structures. The computational modeling used confirmed that lignins derived from more oxygenated monomers have a smaller HOMO-LUMO gap, and therefore are less stable. In the developed study, the replacement of alpha hydroxyl with a carbonyl was able to abruptly change the electron topology, reducing binding energy in βO4 indicating which SHOX model is more susceptible to breakage.

Structural and electronic characteristics of intercalated monopotassium–rubrene: Simulation on a commodity computing cluster

The structural and electronic characteristics of the intercalated monopotassium–rubrene (K1Rub) are studied. In the intercalated K1Rub, one of the two pairs of phenyl groups of rubrene is intercalated by potassium, whereas the other pair remains pristine. This structural feature facilitates the comparison of the electronic structures of the intercalated and pristine pairs of phenyl groups. It is found that, in contrast to potassium adsorption to rubrene, the potassium intercalation promotes the carbon [Formula: see text] orbitals of the intercalated pair of phenyls to participate in the electronic structures of HOMO. Additionally, this intercalated K1Rub is used as a testing vehicle to study the performance of a commodity computing cluster built to run the General Atomic and Molecular Electronic Structure System (GAMESS) simulation package. It is shown that, for many frequently encountered simulation tasks, the performance of the commodity computing cluster is comparable with a massive computing cluster. The high performance-cost-ratio of the computing clusters constructed with commodity hardware suggests a feasible alternative for research institutes to establish their computing facilities.