Towards in silico liquid crystals. Realistic transition temperatures and physical properties for n-cyanobiphenyls via molecular dynamics simulations.

We study the important n-cyanobiphenyl (with n= 4-8) series of mesogens, using modelling and molecular dynamics simulations. We are able to obtain spontaneously ordered nematics upon cooling isotropic samples of 250 molecules. By using the united-atom force field developed herein, we show that the experimental isotropic-nematic transition temperatures are reproduced within 4 K, allowing a molecular-level interpretation of the odd-even effect along the series. Other properties, like densities, orientational order parameters and NMR residual dipolar couplings are also reproduced well, demonstrating the feasibility of predictive in silico modelling of nematics from the molecular structure.

[1]  C. Zannoni,et al.  A deformable Gay–Berne model for the simulation of liquid crystals and soft materials , 2006 .

[2]  G. R. Luckhurst,et al.  The Molecular physics of liquid crystals , 1979 .

[3]  T. Darden,et al.  A smooth particle mesh Ewald method , 1995 .

[4]  M. Cook,et al.  Simulation studies of dipole correlation in the isotropic liquid phase , 2000 .

[5]  C. Zannoni,et al.  Can the pi-facial selectivity of solvation be predicted by atomistic simulation? , 2005, Journal of the American Chemical Society.

[6]  I. Haller.  Thermodynamic and static properties of liquid crystals , 1975 .

[7]  N. Clark,et al.  Microscopic structure and dynamics of a partial bilayer smectic liquid crystal. , 2001, Physical review. E, Statistical, nonlinear, and soft matter physics.

[8]  S. Yakovenko,et al.  Temperature dependence of the properties of simulated PCH5 , 1998 .

[9]  Claudio Zannoni,et al.  Molecular design and computer simulations of novel mesophases , 2001 .

[10]  Mark R. Wilson,et al.  Molecular orientational and dipolar correlation in the liquid crystal mixture E7: a molecular dynamics simulation study at a fully atomistic level. , 2007, Physical chemistry chemical physics : PCCP.

[11]  Nuclear Magnetic Resonance of Liquid Crystals , 1994 .

[12]  J. Banavar,et al.  Computer Simulation of Liquids , 1988 .

[13]  G. R. Luckhurst,et al.  Nuclear spin-lattice relaxation rates in liquid crystals , 1986 .

[14]  A. Komolkin,et al.  Molecular dynamics simulation of a nematic liquid crystal , 1994 .

[15]  Laxmikant V. Kalé,et al.  Scalable molecular dynamics with NAMD , 2005, J. Comput. Chem..

[16]  A. Komolkin,et al.  LOCAL STRUCTURE IN ANISOTROPIC SYSTEMS DETERMINED BY MOLECULAR DYNAMICS SIMULATION. APPLICATION TO A NEMATIC LIQUID CRYSTAL , 1995 .

[17]  B. Bahadur,et al.  Liquid Crystals — Applications and Uses: (Volume 1) , 1990 .

[18]  M. Cook,et al.  Development of an All-Atom Force Field for the Simulation of Liquid Crystal Molecules in Condensed Phases (LCFF) , 2001 .

[19]  John W. Goodby,et al.  Handbook of liquid crystals , 1998 .

[20]  C. Zannoni,et al.  Can nematic transitions be predicted by atomistic simulations? A computational study of the odd-even effect. , 2004, Chemphyschem : a European journal of chemical physics and physical chemistry.

[21]  I. Cacelli,et al.  How the Odd-Even Effects on the Inter-Molecular Potentials Propagate to the Order Parameter in the 4-Cyano-4′n-Alkylbiphenyl Series , 2007 .

[22]  G. Prampolini,et al.  Modeling a liquid crystal dynamics by atomistic simulation with an ab initio derived force field. , 2006, The journal of physical chemistry. B.

[23]  P. Kollman,et al.  Atomic charges derived from semiempirical methods , 1990 .

[24]  M. Parrinello,et al.  Crystal structure and pair potentials: A molecular-dynamics study , 1980 .

[25]  D. Bauman,et al.  Influence of the alkyl chain length of some mesogenic molecules on their Langmuir film formation ability , 2006 .

[26]  U. Singh,et al.  A NEW FORCE FIELD FOR MOLECULAR MECHANICAL SIMULATION OF NUCLEIC ACIDS AND PROTEINS , 1984 .

[27]  S. Meiboom,et al.  Nuclear magnetic resonance in liquid crystals. , 1968, Science.

[28]  S. Chandrasekhar,et al.  Handbook of liquid crystals , 2015 .

[29]  R. Eppenga,et al.  Monte Carlo study of the isotropic and nematic phases of infinitely thin hard platelets , 1984 .

[30]  C. Zannoni,et al.  A multitechnique maximum entropy approach to the determination of the orientation and conformation of flexible molecules in solution , 1998 .

[31]  Shin‐Tson Wu,et al.  Optical and electro‐optic properties of cyanotolanes and cyanostilbenes: Potential infrared liquid crystals , 1988 .

[32]  I. Cacelli,et al.  Atomistic simulation of a nematogen using a force field derived from quantum chemical calculations. , 2005, The journal of physical chemistry. B.

[33]  P. Semenza.  Can anything catch TFT LCDs , 2007 .

[34]  J. Emsley,et al.  Comparison of the maximum entropy and additive potential methods for obtaining rotational potentials from the NMR spectra of samples dissolved in liquid crystalline solvents. The case of 4-nitro-1-(.beta.,.beta.,.beta.-trifluoroethoxy)benzene , 1993 .

[35]  C. Zannoni,et al.  A Monte Carlo investigation of the Lebwohl-Lasher lattice model in the vicinity of its orientational phase transition , 1986 .

[36]  Andrew P. J. Emerson,et al.  Monte Carlo investigations of a Gay—Berne liquid crystal , 1993 .

[37]  G. R. Luckhurst,et al.  The potential of mean torque for flexible mesogenic molecules. Determination of the interaction parameters from carbon–hydrogen dipolar couplings for 4‐n‐alkyl‐4′‐cyanobiphenyls , 1987 .

[38]  O. Lavrentovich,et al.  Defects in Liquid Crystals: Computer Simulations, Theory and Experiments , 2001 .

[39]  Peter G. Bolhuis,et al.  Tracing the phase boundaries of hard spherocylinders , 1997 .

[40]  E. Cebe,et al.  Molecular dynamic study of the odd-even effect in some 4-n-alkyl-4'-cyanobiphenyls. , 2006, Physical review. E, Statistical, nonlinear, and soft matter physics.

[41]  Simon Hanna,et al.  Atomistic simulation of a model liquid crystal. , 2006, The Journal of chemical physics.

[42]  Shri Singh,et al.  Phase transitions in liquid crystals , 2000 .

[43]  Piero Procacci,et al.  ORAC: A Molecular dynamics program to simulate complex molecular systems with realistic electrostatic interactions , 1997 .

[44]  A. Ghanadzadeh.  Dielectric investigations and molecular association in non-mesogenic and mesogenic solutions , 2003 .

[45]  Claudio Amovilli,et al.  Calculation of the intermolecular energy of large molecules by a fragmentation scheme: Application to the 4-n-pentyl-4′- cyanobiphenyl (5CB) dimer , 2002 .

[46]  W. H. Jeu,et al.  The order parameters and in nematic p-alkyl-p' -cyano-biphenyls : polarized Raman measurements and the influence of molecular association , 1985 .

[47]  W. H. Jeu,et al.  A molecular dynamics study of the nematic phase of 4-n-pentyl-4'-cyanobiphenyl , 1989 .

[48]  G. W. Gray,et al.  Molecular theories and structure. Some effects of molecular structural change on liquid crystalline properties , 1971 .

[49]  B. Fung,et al.  Nematic ordering of 4‐n‐alkyl‐4’‐cyanobiphenyls studied by carbon‐13 NMR with off‐magic‐angle spinning , 1986 .

[50]  J. A. Lupo,et al.  Large scale molecular dynamics simulations of a 4-n-pentyl-4′-cyanobiphenyl (5CB) liquid crystalline model in the bulk and as a droplet , 2001 .

[51]  Jorge Peláez,et al.  Atomistic simulations of a thermotropic biaxial liquid crystal. , 2006, Physical review letters.

[52]  C. Glorieux,et al.  Determination of the order parameter and its critical exponent for nCB (n=5–8) liquid crystals from refractive index data , 2004 .

[53]  M. Wilson.  Molecular simulation of liquid crystals: progress towards a better understanding of bulk structure and the prediction of material properties. , 2007, Chemical Society reviews.

[54]  J. W. Emsley,et al.  Nuclear magnetic resonance of liquid crystals , 1984 .

[55]  Mine Ilk Capar,et al.  Odd–even effects in the homologous series of alkyl‐cyanobiphenyl liquid crystals: A molecular dynamic study , 2007, J. Comput. Chem..

[56]  A. V. Zakharov,et al.  Structure and elastic properties of a nematic liquid crystal: A theoretical treatment and molecular dynamics simulation , 2001 .

[57]  Mark R. Wilson,et al.  Progress in computer simulations of liquid crystals , 2005 .

[58]  J. Pablo,et al.  Segmental dynamics in a blend of alkanes: Nuclear magnetic resonance experiments and molecular dynamics simulation , 2002 .

[59]  Juan J. de Pablo,et al.  ON THE SIMULATION OF VAPOR-LIQUID EQUILIBRIA FOR ALKANES , 1998 .

[60]  R. Dabrowski,et al.  Comparison of the dielectric properties of 4-(2-methylbutyl)-4′-cyanobiphenyl (5*CB) and 4-pentyl-4′-cyanobiphenyl (5CB) in the liquid state , 1999 .

[61]  M. Wilson.  MOLECULAR MODELLING OF LIQUID CRYSTAL SYSTEMS : AN INTERNAL COORDINATE MONTE CARLO APPROACH , 1996 .

[62]  Birendra Bahadur,et al.  Liquid Crystals — Applications and Uses , 1992 .

[63]  S. Hanna,et al.  ATOMISTIC COMPUTER SIMULATIONS OF TERRACED WETTING OF MODEL 8CB MOLECULES AT CRYSTAL SURFACES , 2004 .

[64]  W. H. Jeu,et al.  Physical properties of liquid crystalline materials , 1980 .

[65]  W. L. Jorgensen,et al.  Development and Testing of the OPLS All-Atom Force Field on Conformational Energetics and Properties of Organic Liquids , 1996 .

[66]  H. Berendsen,et al.  Molecular dynamics with coupling to an external bath , 1984 .

[67]  R. Horn,et al.  Refractive indices and order parameters of two liquid crystals , 1978 .

[68]  I. Cacelli,et al.  Liquid crystal properties of the n-alkyl-cyanobiphenyl series from atomistic simulations with ab initio derived force fields. , 2007, The journal of physical chemistry. B.

[69]  J. Crain,et al.  Simulating Molecular Properties of Liquid Crystals , 2007 .

[70]  Christopher M. Care,et al.  Computer simulation of liquid crystals , 2005 .

[71]  M. E. Rose,et al.  Elementary Theory of Angular Momentum , 1957 .

[72]  G. W. Gray,et al.  Physical Properties of Liquid Crystals , 2003 .