The simulation of condensed phases in cyclohexane clusters

Trew, Arthur; Pawley, G. S.; Cairns-Smith, A. G.

doi:10.1107/s0108767390008777

Cited by 15 publications

(10 citation statements)

References 16 publications

(17 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At low temperatures in the MD runs it is very short in comparison with the librational damping time seen in Figure 2. A more intuitively agreeable relaxation time of the diffusing, oscillating molecules is ZD, derived according to the model of a diffusing Langevin librator (see Appendix) where zD = 2Z/[( -(E2 -16k,J)"2] (7) At 130 K the result ZD = 0.7 ps is 35-fold larger than t33 and corresponds plausibly with the damping evident in Figure 2 (which damping was not used in the evaluation of ZD). When the temperature rises to 205 K, the temperature of the highresolution neutron study, however, the extrapolated value of (E2 -1 6 k d becomes negative, implying a damped oscillatory behavior of the quantity ([&t-to)]*), and a only a single relaxation is given by the model, that corresponding to 2 3 3 .…”

Section: Discussionmentioning

confidence: 61%

“…Pawley and co-workers, in particular, have published a number of illuminating conclusions based on MD studies of plastically crystalline substances. [2][3][4][5][6][7][8][9] The aim of the present paper is to examine what can be learned about molecular motions in the tetragonal phase1011 of tertbutyl chloride from an MD investigation. Our attention was drawn to this orientationally disordered phase III of the material when we found it possible to monitor the kinetics of the solidstate phase change between phase III and phase IV (ordered monoclinic) in clusters undergoing evaporative cooling in supersonic flow.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Molecular Motions in Plastically Crystalline Clusters of Tetragonal tert-Butyl Chloride. A Molecular Dynamics Study

Chen¹,

Bartell²

1995

J. Phys. Chem.

View full text Add to dashboard Cite

The interior of a 188-molecule cluster of tert-butyl chloride was examined in detail by molecular dynamics computations covering the range of temperature over which the cluster's orientationally disordered phase IV is stable. The aim was to characterize the molecular behavior in a bulklike region in order to interpret the kinetics of the spontaneous transformation to the ordered monoclinic phase occurring at colder temperatures. Of particular concern were the rotational motions about molecular 3-fold axes dictating molecular jump rates in the transition. The activation energy for rotational diffusion, mean librational frequencies, coefficients of rotational diffusion, and relaxation times were derived from the simulations by analyzing results in terms of a model based on a single rotational force constant and coefficient of friction. Prior experimental evidence about these quantities obtained by NMR, cold neutron diffraction, and dielectric techniques had been somewhat contradictory. A reasonable agreement was obtained between computational results and a subset of the experimental results.

show abstract

Section: Discussionmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Molecular Motions in Plastically Crystalline Clusters of Tetragonal tert-Butyl Chloride. A Molecular Dynamics Study

Chen¹,

Bartell²

1995

J. Phys. Chem.

View full text Add to dashboard Cite

show abstract

“…Apart from the easy calculation, due to the absence of boundary conditions, it is thought that such simulations can be of interest for modelling surface initiated transitions (such as melting, for instance) and also in the search for metastable phases. Indeed, the stabilization of metastable phases, as observed by Trew et al in cyclohexane [17], might be due to a finite-size effect. The free cluster simulation would eventually become complementary to the constant-stress cyclic boundary technique of Parrinello and Rahman [20].…”

Section: The Free Cluster Methodsmentioning

confidence: 93%

“…Cluster simulation has been shown to be successful in modelling phase transitions in SF 6 and SeF 6 [10,12,13,16] and cyclohexane [17]. In all cases, it has been shown that the bulk properties are essentially repeated in the centre of a cluster containing as few as 128 molecules.…”

Section: The Free Cluster Methodsmentioning

confidence: 98%

The hexagonal phase of sulfur hexafluoride by molecular dynamics simulation of free clusters

et al. 1992

View full text Add to dashboard Cite

The low temperature structures of sulfur hexafluoride have been investigated by molecular dynamics (MD) simulation, using the free duster method. Clusters containing 229 molecules and having an initial BCC structure can transform either into a stable monoclinic structure identical to that of the bulk material or into an hexagonal structure, depending on the cooling procedure. The hexagonal phase is stable, in the MD time scale, below 65 K. In the range of 70-85 K it experiences a spontaneous transformation into the (monoclinic + cubic) intermediate structure which is known to be stable in such clusters. Essentially identical results have been obtained for a duster containing 137 molecules. This, together with the fact that the parameters of the hexagonal structure obtained here are in good agreement with those obtained experimentally on a thin single crystal, favours the hypothesis of the existence of a metastable hexagonal phase in solid SF 6.

show abstract

“…So far, there have been a number of experimental investigations carried out using different siliceous materials (mainly, MCM-41, SBA-15, and Vycor glass) and a wide variety of molecular gases such as hydrogen (H 2 ), , nitrogen (N 2 ), oxygen (O 2 ), ,– neon (Ne), , argon (Ar), ,– krypton (Kr), carbon monoxide (CO), , and carbon dioxide (CO 2 ) as well as organic molecules such as carbon tetrachloride (CCl 4 ), – nitrobenzene (C 6 H 5 NO 2 ), , benzene (C 6 H 6 ), – cyclohexane (C 6 H 12 ), ,,, water (H 2 O), – and metallic indium (In), mercury (Hg), – and gallium (Ga). , Computer simulations and theoretical investigations have shed much light on the molecular details underlying the structural and dynamic behavior in this highly confined regime. ,,, …”

Section: Introductionmentioning

confidence: 99%

Thermal Stability of Nanocrystals Confined in Nanoporous Media

Lang

Han

2009

J. Phys. Chem. C

View full text Add to dashboard Cite

Thermal stability of nanocrystals confined in nanopores is dramatically different from their bulk counterparts. To understand the underlying mechanism and factors that dominate the general trend of tunability, we have established a simple and unified model for size and interface effects on the thermal stability of nanocrystals based on the perspective of Lindemann’s criterion for melting. According to this model, the depression or enhancement of thermal stability of nanoconfined crystals has been illustrated to depend on the confluence effect of size and interfacial conditions. Model predictions are consistent with available experimental results for molecular gases (oxygen, neon, argon, and krypton), organic molecules (benzene, nitrobenzene, carbon tetrachloride, and cyclohexane), water, and metallic (gallium, indium, and mercury) nanocrystals confined in nanoporous media.

show abstract

The simulation of condensed phases in cyclohexane clusters

Cited by 15 publications

References 16 publications

Molecular Motions in Plastically Crystalline Clusters of Tetragonal tert-Butyl Chloride. A Molecular Dynamics Study

Molecular Motions in Plastically Crystalline Clusters of Tetragonal tert-Butyl Chloride. A Molecular Dynamics Study

The hexagonal phase of sulfur hexafluoride by molecular dynamics simulation of free clusters

Thermal Stability of Nanocrystals Confined in Nanoporous Media

Contact Info

Product

Resources

About