Communication: Physical origins of ionization potential shifts in mixed carboxylic acids and water complexes

Energy decomposition analysis based on broken symmetry unrestricted density functional theory

In this paper, the generalized Kohn-Sham energy decomposition analysis (GKS-EDA) scheme is extended to molecular interactions in open shell singlet states, which is a challenge for many popular EDA methods due to the multireference character. Based on broken symmetry (BS) unrestricted density functional theory with a spin projection approximation, the extension scheme, named GKS-EDA(BS) in this paper, divides the total interaction energy into electrostatic, exchange-repulsion, polarization, correlation, and dispersion terms. Test examples include the pancake bond in the phenalenyl dimer, the ligand interactions in the Fe(ii)-porphyrin complexes, and the radical interactions in dehydrogenated guanine-cytosine base pairs and show that GKS-EDA(BS) is a practical EDA tool for open shell singlet systems.

Quantitative probing of subtle interactions among H-bonds in alpha hydroxy carboxylic acid complexes

The alpha OH stretching frequency may be affected upon complexing with water and formic acid.

Dissection of H-bonding interactions in a glycolic acid–water dimer

The binding strength and collective effects of multiple H-bonds in the glycolic acid–water dimer were studied in comparison to the aromatic analog, 9-hydroxy-9-fluorene carboxylic acid (9HFCA).

Unravelling hydrogen bonding interactions of tryptamine–water dimer from neutral to cation

The physical origin for the three intermolecular hydrogen bonds in the neutral and cationic forms of the tryptamine–water dimer is explored.