Density functional study of polypropylene and its submolecules

Abstract

Articles you may be interested in Density functional theory study of self-association of N -methylformamide and its effect on intramolecular and intermolecular geometrical parameters and the cis/trans population A density functional study of crystalline acetic acid and its proton transfer polymorphic forms A density functional theory study of vibrational coupling between ribose and base rings of nucleic acids with ribosyl guanosine as a model system Previous density functional ͑DF͒ calculations of the structures of small hydrocarbon molecules ͑CH, CH 2 , C 2 H 2 , C 2 H 4 , C 3 H 6 , C 3 H 8 ) have been extended to larger systems. The structure of a single chain of isotactic polypropylene (it-PP͒ has been optimized, and calculations have been performed for smaller molecules with closely related structures ͑propane C 3 H 8 , several conformers of isopentane C 5 H 12 , and 2,4,6-trimethyl heptane C 10 H 22 ) using both local spin density ͑LSD͒ and non-local ͑gradient-corrected͒ energy functionals. The pronounced transferability of the local structural parameters between C 5 H 12 , C 10 H 22 and it-PP suggests that the energy surfaces calculated for molecules with five carbon atoms should provide a very good representation of the local energy variations in much larger systems.

Polyethylene under tensil load: Strain energy storage and breaking of linear and knotted alkanes probed by first-principles molecular dynamics calculations

“…As a first step, we studied a decane molecule (C 10 H 22 ), which can be taken as representative of longer linear alkanes and, by extrapolation, of polyethylene. The equilibrium structural parameters, reported in Table 1, are in excellent agreement (within 1%) with other DFT results and with experimental data [24,25] for hydrocarbons and/or crystalline polyethylene (PE).…”

Density functional study of molecular crystals: Polyethylene and a crystalline analog of bisphenol-A polycarbonate

“…We optimize the atomic positions at fixed volume and shape of the unit cell by minimizing the forces on all atoms, following the method described in detail previously. 7,9 The electron-ion interaction is represented by ionic pseudopotentials with the ͑non-local͒ form suggested by Troullier and Martins. 20 We use s-nonlocality for the O atom.…”

“…20 We use s-nonlocality for the O atom. Detailed tests of the convergence of the plane wave basis for small organic molecules 6 and PE 7 showed that reliable energy differences can be obtained using a kinetic energy cutoff of 30 a.u. for systems containing H and C, while 35 a.u.…”

“…Hydrocarbons are prototype organic molecules, and their polymers are among the most important. Work performed in our group and elsewhere has indicated that both LSD and gradient-corrected functionals give a reliable description of structures and rotation barriers in small organic molecules 6 and in chains like polypropylene, 7 although both approximations tend to underestimate reaction barriers. 8 In a recent study of the interchain interactions in crystalline polyethylene ͑PE͒, 9 we showed that the LD approximation overestimated the strength of the interchain interactions, while the gradient-corrected form BP led to a complete absence of binding between the chains.…”

Density functional study of carbonic acid clusters

“…10,11 The electron-ion interaction is represented by ionic pseudopotentials with the ͑nonlocal͒ form suggested by Troullier and Martins. 12 We adopt periodic boundary conditions with a simple cubic cell with lattice constant 36 a.u.…”