Shri Siddheshwar College

Manjlegaon, India

Shri Siddheshwar College

Manjlegaon, India
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Deshmukh V.,Shri Siddheshwar College | Naganathappa M.,Gandhi Institute of Technology and Management | Kharat B.,Lbs College | Chaudhari A.,Institute of Science
Optical Materials | Year: 2013

We have studied the structure, vibrational spectra, electronic absorption spectra and first and second hyperpolarizabilities (β and γ) of monosubstituted acetonitrile using quantum chemical methods. The substituents used here are F, Cl, Br, CH3 and NH2. Among different levels of theory used here for the calculations, the geometrical parameters, dipole moment and vibrational frequencies for the acetonitrile at B3LYP/aug-cc-pvdz level are in agreement with the experimental determinations. A large change in the vibrational and electronic absorption spectrum of acetonitrile is observed upon monosubstitution. The bromosubstituted acetonitrile shows the highest β and γ values and absorption intensities in electronic absorption spectrum among different molecules studied here. All the molecules show large HOMO-LUMO gap even for a strong applied field of 0.012 a.u. (>6 eV). The β and γ values of bromoacetonitrile are about 25 and 9 times higher respectively than those for the acetonitrile. © 2012 Elsevier B.V. All rights reserved.


Deshmukh V.,Shri Siddheshwar College | Nagnathappa M.,Gandhi Institute of Technology and Management | Kharat B.,L B S Senior College | Chaudhari A.,Institute of Science
Journal of Molecular Liquids | Year: 2014

Borazine and donor-acceptor substituted borazines have been studied by density functional theory method. We have used NH2 as a donor and NO2, CN, COCl and NMe2 as acceptor groups. The geometrical parameters, vibrational frequencies, NLO properties and electronic absorption spectra have been obtained at B3LYP/6-311++G** level of theory. Calculated structural parameters and vibrational frequencies for borazine at this level of theory are in excellent agreement with the available experimental determinations. The BN stretching mode is the most intense vibrational mode observed in vibrational spectra of borazine and substituted borazines. The vibrational frequency for this mode is observed in a range of 1435 to 1585 cm- 1. For the calculations of first (β) and second (γ) hyperpolarizabilities, the finite field approach has been used. Direction of applied field, method and basis set dependent hyperpolarizabilities are obtained. The hyperpolarizabilities are found to be enhanced upon donor and acceptor substitution in borazine. For all the substituted borazines, the β and γ values are higher than those for the unsubstituted borazine. © 2013 Elsevier B.V.


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.


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

Hydrogen-bonding interaction in acetonitrile oligomers is studied using density functional theory method. Two types of hydrogen-bonded oligomers are considered viz. cyclic and ladder. Different levels are used to optimize the geometry of acetonitrile monomer and found that at B3LYP/aug-cc-pvtz level the geometrical parameters and vibrational frequencies are in agreement with the experimental determinations. The BSSE corrected total energies of acetonitrile oligomers show that the cyclic structures are more stable than the ladder and the hydrogen bonds in former are stronger than those in the latter. Manybody analysis approach was used to study the nature of interactions between different molecules in these oligomers. It is found that the contribution from many-body energies to the binding energy of a complex is different in cyclic and ladder structures. An increase and decrease in the energy per hydrogen bond with cluster size for the cyclic and ladder structures, respectively, indicates the positive and negative hydrogen-bond cooperativity, respectively.© Springer Science+Business Media, LLC 2011.


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.


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.


Chang C.K.,National Chung Cheng University | Deshmukh V.,Shri Siddheshwar College | Chaudhari A.,Institute of Science | Lee S.-L.,National Chung Cheng University
Journal of Computational and Theoretical Nanoscience | Year: 2013

We investigate nonlinear optical properties of linear formaldehyde oligomers (H2CO) n (n = 1∼7) by using quantum chemical methods in comparison with those of ladder formaldehyde oligomers. The finite-field approach and hyperpolarizability density analysis has been used to calculate the static first and second hyperpolarizablitity βxxx and γxxxx. The hyperpolarizability density analysis provides pictorial and intuitive understanding of the spatial contribution to the static hyperpolarzability. Different trend in βxxx and γxxxx values with n is observed for the linear and ladder oligomers. The βxxx and γxxxx values increase with number of formaldehyde molecules in oligomer for the linear oligomers whereas only γxxxx values increase with n for the ladder connection. The NLO properties per n for the linear oligomers are higher than those for the ladder oligomers. Copyright © 2013 American Scientific Publishers. All rights reserved.


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.


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.


PubMed | Shri Siddheshwar College
Type: Journal Article | Journal: 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.

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