A Theoretical Study of Molecular Ordering of Some Smectic Liquid Crystals

Yayloyan, Stepan M.; Bezhanova, L. S.; Yayloyan, Ashot M.

doi:10.1080/10587250108025354

Cited by 53 publications

(19 citation statements)

References 6 publications

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“…The role of molecular interactions in mesomorphic compounds has engrossed the attention of several workers [9][10][11] based on the Rayleigh-Schrodinger perturbation method. These studies were aimed at establishing the anisotropic nature of the pair potential, and subsequently finding out the minimum energy configuration of a pair of liquid crystalline molecules.…”

Section: Introductionmentioning

confidence: 99%

Molecular ordering in a bipolar nematogenic cyanobiphenyl – a computer simulation approach

Praveen¹,

Ojha²

2010

Phase Transitions

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The molecular ordering of 4-(6-hydroxypropyloxy)-4 0 -cyanobiphenyl (H3CBP), a bipolar nematogen, has been carried out at room temperature (300 K) with respect to translatory and orientational motions. The complete neglect differential overlap (CNDO/2) method has been employed to compute the net atomic charge and atomic dipole moment at each atomic center. The modified RayleighSchrodinger perturbation theory 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 interaction energy values obtained through these computations were used to calculate the probability of each configuration at room temperature using the Maxwell-Boltzmann formula. On the basis of stacking, in-plane, and terminal interactions energy calculations, all possible geometrical arrangements of the molecular pair have been considered. Further, an attempt has been made to develop a model for liquid crystallinity based on probability of dimer complexes. IntroductionLiquid crystals (LCs) are indeed a new state of matter where the orientational order of the constituent molecules is coupled to a long-range positional order that is reduced (in smectogens) or absent (in nematogens) compared to that of crystals. A substance in LC state is highly anisotropic in some of its properties but may show a certain degree of fluidity and viscosity, in many situations. These self-organized molecular materials play an important role in materials science: they are model materials in order to investigate the connection between chemical structure and physical properties [1,2]. The understanding of the relationship between microscopic structure and bulk properties is the vital object of study of complex materials, such as LCs. From this point of view, computational studies represent an important tool as the structural and dynamical macroscopic properties can be related to the microscopic interactions described by the adopted model potential [3].The phase behavior of LCs is a subject matter of growing interest not only from the point of view of their technological applications but also from the fundamental studies in

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Section: Introductionmentioning

confidence: 99%

Molecular ordering in a bipolar nematogenic cyanobiphenyl – a computer simulation approach

Praveen¹,

Ojha²

2010

Phase Transitions

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“…This interaction determines the physical properties of liquid crystals, as well as the type of physical and physicochemical process taking place in these substances. The role of molecular interactions in mesogenic compounds has attracted the attention of many workers based on the Rayleigh-Schrodinger perturbation method [2,3,4]. An attempt has been put forward to correlate the mesogenic properties with molecular interactions.…”

Section: Introductionmentioning

confidence: 99%

Molecular ordering of 4O.2 compound in a dielectric medium at room temperature‐A theoretical approach

Ojha

Pisipati²

2004

Cryst. Res. Technol.

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The molecular ordering of N-(4-n-butoxybenzylidene)-4'-ethyaniline [4O.2] in a dielectric medium (benzene) has been carried out on the basis of statistical mechanics and intermolecular forces. The atomic net charge and atomic dipole moment at each atomic centre has been evaluated using the CNDO/2 method. The modified Rayleigh-Schrodinger perturbation theory with multicentered-multipole expansion method has been employed to evaluate the long-range intermolecular interactions, while '6-exp' potential function has been assumed for the short-range interactions. The total interaction energy values obtained through these computations were used to calculate the probability of each configuration in a dielectric medium at room temperature (300K) using the MB-formula. The flexibility of various interacting configuration has been studied in terms of variation of probability due to departure from the most probable configuration. A comparative picture of the molecular parameters like total energy, binding energy and total dipole moment has been given. An attempt has been made to analyse the characteristic features of nematogenic 4O.2 compound in terms of its relative order.

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“…The role of molecular interactions in mesomorphic compounds has received the attention of several workers [8][9][10] based on the Rayleigh-Schrodinger perturbation method. These studies were aimed at establishing the anisotropic nature of the pair potential and subsequently finding out the minimum energy configuration of a pair of liquid-crystalline molecules.…”

Section: Introductionmentioning

confidence: 99%

Ordering of a Strong Polar Nematogen (6CBB) in a Dielectric Medium: A Computational Analysis

Praveen¹,

Ojha²

2010

Molecular Crystals and Liquid Crystals

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A computational analysis of molecular ordering of a strongly polar nematogen 4-cyanobiphenyl-4 0 -hexylbiphenyl carboxylate (6CBB), has been carried out with respect to translational and orientational motions. The atomic net charge and dipole moment at each atomic center have been evaluated using the complete neglect differential overlap (CNDO=2) method. The modified Rayleigh-Schrodinger perturbation theory, along with the multicentered-multipole expansion method, has been employed to evaluate the long-range intermolecular interactions, while the 6-exp potential function has been assumed for short-range interactions. The total interaction energy values obtained through these computations were used as input for calculating the probability of each configuration in a dielectric medium (i.e., noninteracting and nonmesogenic solvent, benzene) at the nematic-isotropic transition temperature (633 K) using the Maxwell-Boltzmann formula. On the basis of stacking, in-plane, and terminal interaction energy calculations, all possible geometrical arrangements of molecular pairs have been considered. It has been observed that the energies are redistributed in a dielectric medium, and there is a considerable rise in the probabilities of interactions, although the order of preference remains the same. The present article provides a new and interesting way of looking at the nematogen in a dielectric medium.

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A Theoretical Study of Molecular Ordering of Some Smectic Liquid Crystals

Cited by 53 publications

References 6 publications

Molecular ordering in a bipolar nematogenic cyanobiphenyl – a computer simulation approach

Molecular ordering in a bipolar nematogenic cyanobiphenyl – a computer simulation approach

Molecular ordering of 4O.2 compound in a dielectric medium at room temperature‐A theoretical approach

Ordering of a Strong Polar Nematogen (6CBB) in a Dielectric Medium: A Computational Analysis

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