Probabilistic and thermodynamic approach on phase behavior of nematic liquid crystals: A comparative study

Das, Punyatoya; Praveen, P. Lakshmi

doi:10.1080/15421406.2017.1373009

Cited by 9 publications

(3 citation statements)

References 13 publications

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“…A detailed computational scheme based on simplified formula by Claverie for the evaluation of interaction energy between a molecular pair has been used to calculate the energy for fixed configuration. 17 According to the second order perturbation theory for intermediate range interactions, the total pair interaction energy of molecules (U pair ) is represented as sum of various terms contributing to the total energy: 18 U pair = U el + U pol + U disp + U rep (1) where U el , U pol , U disp and U rep are the electrostatic, polarisation, dispersion and repulsion energy terms, respectively. Again, electrostatic term is expressed as:…”

Section: Computation Of Interaction Energy At Various Configurationsmentioning

confidence: 99%

Mesophase behaviour of a cyanobiphenyl molecule in polar aprotic solvent: Rigidity effect

Nayak¹,

Praveen²

2020

JPS

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In this paper, a theoretical study has been carried out on a liquid crystal compound named p-n-propyl cyanobiphenyl (3CB). The different modes of interaction energy values in a polar aprotic solvent (ethyl acetate) for small amount of translation and rotation are calculated. The corresponding probabilities have been calculated at both room temperature (300 K) and transition temperature (303.3 K). The rigidity parameter for stacking and in-plane interactions has been estimated and then the stability of molecule according to probability and rigidity at definite translation and rotation has been concluded. The change in the characteristics and stability of the compound at transition temperature has been observed. The dependence of mesophase behaviour with change in the certain configurations and orientation of the molecules have been discussed. These observed results provide an insight about the process of mesophase structure and its formation. The present compound may guide in establishing the other molecular models with transition temperature nearer to room temperature.

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Section: Computation Of Interaction Energy At Various Configurationsmentioning

confidence: 99%

Mesophase behaviour of a cyanobiphenyl molecule in polar aprotic solvent: Rigidity effect

Nayak¹,

Praveen²

2020

JPS

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“…1,2 These are highly sensitive to external fields, boundary effects and thermal fluctuations. [3][4][5] This sensitivity imposes new interesting challenges to be tackled by the entire scientific community and thus widens the avenues of technological applications. To a less-trained person, the term liquid crystal appears quite paradoxical, suggesting the juxtaposition of two distinct liquid and solid states that have defined properties like the fluidity of the former and rigidity of the latter.…”

Section: Introductionmentioning

confidence: 99%

Stability, phase and absorption analysis of 4-alkenyl bicyclohexylnitrile: Thermodynamic and spectroscopic approaches

Sahoo

Sarma²,

Praveen

2021

JPS

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Thermodynamic and spectroscopic approaches have been adopted to analyse the stability, phase and absorption analysis of 4-alkenyl bicyclohexylnitrile. The atomic net charge and dipole moment at each atomic centre have been evaluated using the complete neglect differential overlap (CNDO/2) method. The modified Rayleigh-Schrodinger perturbation theory, along with multicentered-multipole expansion method, has been employed to evaluate long-range intermolecular interactions, while a "6-exp" potential function has been assumed for short-range interactions. The total interaction energy values of the alkenyl compound in tetrahydrofuran (THF) solvent have been calculated and compared with the values of the pure form of the compound. These energy values have been used as the input to calculate the thermodynamic parameters of each configuration at room (300 K) and nematic-isotropic transition (364.7 K). The UV-Visible spectra of the compound in pure form and THF medium have been studied. The phase and UV stabilities of the compound have been discussed.

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“…From the LC literature, one may conclude that there are different kinds of nematic phase [4] among which the local molecular organization is qualitatively different. The research of particular nematogens demands a thorough knowledge of their structure in relation to that of other nematic phases based on theoretical models [5,6] prior to the synthesis as it offers valuable information on phase behaviour. The stability of a given phase is principally governed by the Helmholtz free energy A. Molecular motions (translational, rotational etc.)…”

Section: Introductionmentioning

confidence: 99%

Theoretical Model of a Nematogen: Estimation of Phase Stability, Absorption, Electrochemical, and Nonlinear Optical Properties

Jose¹,

Simi²,

Raju

et al. 2018

Acta Phys. Pol. A

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Theoretical analysis has been presented on a nematogen 4-dimethylaminobenzaldehyde (4-cyanophenylethylidene) hydrazone (E,E) (C18H18N4) to analyze its phase stability. The net atomic charges and dipole moment at each atomic centre has been calculated using complete neglect of differential overlap/spectroscopy method. The modified Rayleigh-Schrödinger perturbation theory along with multicentered-multipole expansion method has been used to evaluate the long-range intermolecular interactions. A "6-exp" potential function has been used for short-range interactions. The total interaction energy values have been used as input to calculate the probability of a particular configuration using the Maxwell-Boltzmann formula. Further, the Helmholtz free energy, and entropy at room temperature (300 K), nematic-isotropic transition temperature (436 K) and above transition temperature (500 K) have been computed. An attempt has been made to understand the phase stability and behaviour of the molecule. UV absorption spectra have been calculated using complete neglect of differential overlap/spectroscopy, and intermediate neglect of differential overlap/spectroscopy methods. The observed π → π * transitions, electrochemical properties based on highest occupied molecular orbital, lowest unoccupied molecular orbital energies, and principal polarizability components, and anisotropy of polarizability have been reported to understand the kinetic stability, global reactivity, and non-linear optical activity of the molecule.

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Probabilistic and thermodynamic approach on phase behavior of nematic liquid crystals: A comparative study

Cited by 9 publications

References 13 publications

Mesophase behaviour of a cyanobiphenyl molecule in polar aprotic solvent: Rigidity effect

Mesophase behaviour of a cyanobiphenyl molecule in polar aprotic solvent: Rigidity effect

Stability, phase and absorption analysis of 4-alkenyl bicyclohexylnitrile: Thermodynamic and spectroscopic approaches

Theoretical Model of a Nematogen: Estimation of Phase Stability, Absorption, Electrochemical, and Nonlinear Optical Properties

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