@article {43241, title = {Non-covalent interactions in extended systems described by the effective fragment potential method: theory and application to nucleobase oligomers}, journal = {Journal of Physical Chemistry A}, volume = {114}, year = {2010}, month = {NOV}, abstract = {The implementation of the effective fragment potential (EFP) method within the Q-CHEM electronic structure package is presented. The EFP method is used to study noncovalent π-π and hydrogen-bonding interactions in DNA strands. Since EFP is a computationally inexpensive alternative to high-level ab initio calculations, it is possible to go beyond the dimers of nucleic acid bases and to investigate the asymptotic behavior of different components of the total interaction energy. The calculations demonstrated that the dispersion energy is a leading component in π-stacked oligomers of all sizes. Exchange-repulsion energy also plays an important role. The contribution of polarization is small in these systems, whereas the magnitude of electrostatics varies. Pairwise fragment interactions (i.e., the sum of dimer binding energies) were found to be a good approximation for the oligomer energy.}, author = {Ghosh, Debashree and Kosenkov, Dmytro and Vanovschi, Vitalii and Williams, Christopher F. and Herbert, John M. and Gordon, Mark S. and Schmidt, Michael W. and Slipchenko, Lyudmila V. and Krylov, Anna I.} } @article {43817, title = {Nature of selenium hydrogen bonding: gas phase spectroscopy and quantum chemistry calculations}, journal = {Physical chemistry Chemical physics}, volume = {19}, year = {2017}, month = {SEP}, pages = {24179-24187}, type = {Article}, abstract = {

Subsequent to the recent re-definition of hydrogen bonding by the IUPAC committee, there has been a growing search for finding the presence of this ever interesting non-covalent interaction between a hydrogen atom in an X-H group and any other atom in the periodic table. In recent gas phase experiments, it has been observed that hydrogen bonding interactions involving S and Se are of similar strength to those with an O atom. However, there is no clear explanation for the unusual strength of this interaction in the case of hydrogen bond acceptors which are not conventional electronegative atoms. In this work, we have explored the nature of Se hydrogen bonding by studying indole...dimethyl selenide (indmse) and phenol...dimethyl selenide (phdmse) complexes using gas phase IR spectroscopy and quantum chemistry calculations. We have found through various energy decomposition analysis (EDA) methods and natural bond orbital (NBO) calculations that, along with electrostatics and polarization, charge transfer interactions are important to understand Se/S hydrogen bonding and there is a delicate balance between the various interactions that plays the crucial role rather than a single component of the interaction energy. An in-depth understanding of this type of non-covalent interaction has immense significance in biology as amino acids containing S and Se are widely present in proteins and hence hydrogen bonding interactions involving S and Se atoms contribute to the folding of proteins.

}, keywords = {Center-Dot-O, Clusters, Co-Ordination, Complexes, intermolecular interactions, Proteins, Replacement, spectra, Strength, Sulfur}, issn = {1463-9076}, doi = {10.1039/c7cp05265k}, author = {Mishra, Kamal K. and Singh, Santosh K. and Ghosh, Paulami and Ghosh, Debashree and Das, Aloke} }