Ab Initio Calculations on Small Molecule Analogs of Polycarbonates

Sun, Hao; Mumby, Stephen J.; Maple, Jon R.; Hagler, A. T.

doi:10.1021/j100016a022

Cited by 155 publications

(120 citation statements)

References 10 publications

Supporting

Mentioning

116

Contrasting

Order By: Relevance

“…[27][28][29] A cubic cell containing four polymer chains of 25 monomers each was constructed at 580 K by means of the Amorphous Cell protocol 30,31 with periodic boundary conditions. The tacticity of the chains was close to 80%.…”

Section: Simulation Methodsmentioning

confidence: 99%

Self- and Collective Dynamics of Syndiotactic Poly(methyl methacrylate). A Combined Study by Quasielastic Neutron Scattering and Atomistic Molecular Dynamics Simulations

et al. 2006

View full text Add to dashboard Cite

We have investigated the molecular dynamics of syndiotactic poly(methyl methacrylate) well above the glass transition by combining quasielastic neutron scattering and fully atomistic computer simulations. The incoherent scattering measured by backscattering on a sample with deuterated ester methyl groups has revealed the single-particle motions of hydrogens in the main chain and in the R-methyl groups. Moreover, with neutron spin-echo experiments on the fully deuterated sample we have accessed the collective motions at the two first maxima of the structure factor. The simulated cell, which has been previously validated regarding the structural properties et al. Macromolecules 2006, 39, 3947], shows a dynamical behavior that, allowing a shift in temperature, reproduces very accurately all the experimental results. The combined analysis of both sets of data has shown that: (i) The segmental relaxation involving backbone atoms deviates from Gaussian behavior.(ii) The dynamics is extremely heterogeneous: in addition to the subdiffusion associated with the R-process and the methyl group rotations, we have found indications of a rotational motion of the ester side group around the main chain. (iii) At a given momentum transfer and depending on the molecular groups considered, the time scales for collective motion are spread over about 1 order of magnitude, the correlations involving the main chain decaying much more slowly than those relating side groups. (iv) At the length scale characteristic for the overall periodicity of the system (that corresponding to the first structure factor peak), the experimentally observed collective dynamics relates to the backbone motions and is of interchain character; there, coherency effects are observed for all correlations, though side groups display weaker collectivity. (v) At the second structure factor peak, coherency remains only for correlations involving the main chains.

show abstract

Section: Simulation Methodsmentioning

confidence: 99%

Self- and Collective Dynamics of Syndiotactic Poly(methyl methacrylate). A Combined Study by Quasielastic Neutron Scattering and Atomistic Molecular Dynamics Simulations

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Atomic charges were assigned by the PCFF force field [24][25][26] . The geometry optimizations were performed with the Conjugate Gradient method with an RMS force criterion of 0.001 kcal mol À1 Å…”

Section: Force Field Calculationsmentioning

confidence: 99%

Solid‐State Supramolecular Organization of Polythiophene Chains Containing Thienothiophene Units

et al. 2009

View full text Add to dashboard Cite

We use molecular modeling and the simulation of X‐ray diffraction patterns to determine the molecular packing of a thiophene‐based polymer showing exceptionally high field‐effect mobilities (up to 1 cm2 V−1 s−1). We focus on the organization of the polymer chains in lamellae and the orientation of these crystalline domains with respect to the substrate in thin films. The analysis is supported by XRD and NEXAFS experiments and is complemented by calculating intermolecular transfer integrals, which govern the charge mobility.

show abstract

“…For completeness we provide ͑Table I͒ the structural parameters and energy differences calculated using the present method, as well as the results of other calculations. 1,21 The small energy differences involved in the reaction of water and carbon dioxide mean that vibrational zero point energy ͑ZPE͒ corrections are important. 2 2 The strength of the two hydrogen bonds is reflected in small but significant changes in the structure of the constituent monomers: the CvO bond increases from 1.22 Å in the monomer to 1.25 Å in the dimer, the C-O bond shrinks from 1.35 Å to 1.32 Å, and the bond angles change slightly to adapt to the formation of the hydrogen bonds.…”

Section: A Monomers Dimermentioning

confidence: 99%

Density functional study of carbonic acid clusters

Ballone

Montanari

Jones

2000

The Journal of Chemical Physics

View full text Add to dashboard Cite

Density functional calculations on carbonic acid H 2 CO 3 are extended to clusters of up to five such units. The most stable forms are the linear, hydrogen-bonded analogs of the dimer with anti-anti orientation. We calculate structures and vibration frequencies, as well as the energy required to bend and stretch the linear isomers. Linear chains of up to ϳ20 units should be favored over ring structures, and they have a tensile strength reminiscent of chains of water molecules. We also discuss planar, nonlinear structures as well as three-dimensional isomers.

show abstract

Ab Initio Calculations on Small Molecule Analogs of Polycarbonates

Cited by 155 publications

References 10 publications

Self- and Collective Dynamics of Syndiotactic Poly(methyl methacrylate). A Combined Study by Quasielastic Neutron Scattering and Atomistic Molecular Dynamics Simulations

Self- and Collective Dynamics of Syndiotactic Poly(methyl methacrylate). A Combined Study by Quasielastic Neutron Scattering and Atomistic Molecular Dynamics Simulations

Solid‐State Supramolecular Organization of Polythiophene Chains Containing Thienothiophene Units

Density functional study of carbonic acid clusters

Contact Info

Product

Resources

About