Entity

Time filter

Source Type

Manjlegaon, India

Kharat B.,Lbs Sr College | Deshmukh V.,Shri Siddheshwar College | Chaudhari A.,Institute of Science
Journal of Molecular Liquids | Year: 2013

The hydrogen bond cooperativity effects in cyclic and ladder oligomers of cyanamide are studied using density functional theory (DFT) method. Among different levels of theory used here, the geometrical parameters for cyanamide monomer at B3LYP/aug-cc-pvdz level are in excellent agreement with the experimental determinations. Cyclic oligomers are found to be more stable than the ladder, and the hydrogen bonds in the former are stronger than those in the latter. The hydrogen bond cooperativity effects are discussed in terms of the strength of hydrogen bonds, energy per hydrogen bond, excess energy, inter- and intra-molecular distances and vibrational frequencies. The positive and negative hydrogen bond cooperativity effects are found for the cyclic and ladder oligomers, respectively. We also report hyperpolarizabilities for these oligomers. © 2013 Elsevier B.V. Source


Kharat B.,L B S Senior College | Deshmukh V.,Shri Siddheshwar College | Chaudhari A.,Dr. Babasaheb Ambedkar Marathwada University | Chaudhari A.,Institute of Science
Journal of Computational and Theoretical Nanoscience | Year: 2013

We have investigated the structure, vibrational spectrum and static first (β) and second (γ) hyperpolarizabilities of cyanamide in singlet, triplet and quintet state using Density functional Theory method. The Finite-Field approach has been used to obtain the static first and second hyperpolarizabilities by applying the field in a Z-direction. We have chosen a field strength of 0.008 a.u. to calculate the first and second hyperpolarizabilities of a cyanamide. Cyanamide shows the lowest energy at B3LYP/aug-cc-pvdz level among different levels used here. The geometrical parameter and vibrational frequencies obtain at this level are in close agreement with the experimental determinations. Out of the nine vibrational modes, seven modes in triplet and eight in quintet state are red shifted than those in a singlet state. The only blue shifted mode in quintet is the C-N stretching mode with a blue shift of 220 cm-1 than that for the singlet. The γ values of cyanamide in triplet and quintet state are increased by about 2400 a.u. than the singlet state using electron correlation method. The HOMO-LUMO gap in a singlet state is larger than that for the triplet and quintet state. Copyright © 2013 American Scientific Publishers. Source


Kharat B.,L B S Sr College | Deshmukh V.,Shri Siddheshwar College | Chaudhari A.,Institute of Science
Journal of Molecular Liquids | Year: 2013

We studied cyclic and ladder type hydrogen bonded oligomers of acetonitrile using Density Functional Theory method. The structural parameters, interaction energies and vibrational frequencies for the monomer at B3LYP/aug-cc-pvdz level are in agreement with the available experimental determinations. In case of cyclic oligomers, five modes are blue and three red shifted than the corresponding modes in monomer. For the ladder oligomers, six modes are blue and three red shifted than the monomer. The finite field method has been used to obtain hyperpolarizabilities for the oligomers. The dipole moment of ladder dimer and tetramer is found to be zero due to the centrosymmetry. The β values are close to zero for both types of oligomers whereas γ values are increased with an increase in number of monomeric molecules in oligomers. © 2012 Elsevier B.V. All rights reserved. Source


Deshmukh V.,Shri Siddheshwar College | Lee S.-L.,National Chung Cheng University | Chaudhari A.,Institute of Science
Journal of Molecular Modeling | Year: 2012

This work reports hydrogen bonding interaction in linear formaldehyde oligomers using density functional theory method. Many-body analysis technique has been used to study the various interactions in these oligomers and to obtain % contributions from individual many-body energy terms to the binding energies of these oligomers. Co-operativity effects are studied using different indicators viz. hydrogen bond strength, inter- and intramolecular distances, dissociation energy, dipole co-operativity, energy per hydrogen bond, excess energy and non-additive energy. All these indicators show strong positive hydrogen bond co-operativity in linear formaldehyde oligomers. The dipole moment changes from 2.51 D in monomer to 20.92 D in formaldehyde heptamer. © Springer-Verlag 2012. Source


Kharat B.,L B S Sr College | Deshmukh V.,Shri Siddheshwar College | Chaudhari A.,Swami Ramanand Teerth Marathwada University
Structural Chemistry | Year: 2012

This work reports hydrogen bonding interaction in cyclic and ladder oligomers using density functional theory method. Many-body analysis technique has been used to study the nature of interactions between different molecules and their contribution to the binding energy of a respective hydrogen bonded oligomers. Hydrogen bonds in cyclic trimer to pentamer are stronger than those in corresponding ladder structures. Cyanamide monomer shows the lowest energy at B3LYP/aug-cc-pvdz level among different methods used here with the same basis set. The geometrical parameters for cyanamide monomer obtained at B3LYP/aug-cc-pvdz level are in excellent agreement with the experimental determinations. Cyclic structures are more stable than the ladder. In cyclic oligomers not only total two-body energies, but higher body energies also contribute significantly to the binding energy of a respective complex whereas in ladder, only total two-body energies contribute significantly and higher-body energies are almost negligible for cyanamide trimer to pentamer. © Springer Science+Business Media, LLC 2011. Source

Discover hidden collaborations