Ab initio and classical atomistic modelling of structure and defects in crystalline orthorhombic polyethylene: Twin boundaries, slip interfaces, and nature of barriers

Ab initioinvestigation of monoclinic phase stability and martensitic transformation in crystalline polyethylene

“…Thus, to reduce the energy, the chains are forced to tilt such that the H-H separation is increased. Moreover, such rotations reduce the regions of low charge density and lead to more uniform charge density distributions, which in previous investigations have been found to correlate strongly with reducing the ground state energy in PE [21]. Once in this tilted state, the closely spaced H atoms pin the chains and prevent them from wiggling freely, which FIG.…”

“…Also, it has shown high predictive capabilities in terms of reproducing the librational phonon modes of organic crystals [61] and robustness when it comes to providing restoring forces for strained bond lengths [62]. For the case of PE, the vdW-DF-cx functional has shown an ability to predict both the lattice parameters and elastic constants of orthorhombic PE in good agreement with experimental data, where local or semilocal formulations, such as conventional LDA or GGA, fail [21]. Finally, as demonstrated below, in the present work we observed a good agreement between experimental and vdW-DF-cx characterizations of the orthorhombic phonon data.…”

“…Yielding of amorphous polymers is characterized by slippage of the random chains, and the response depends strongly on the chain entanglements. On the other hand, for crystalline PE three important crystal plastic mechanisms have been identified: (i) slip [8][9][10][11][12][13][14][15][16][17][18][19][20][21], (ii) twinning [8,13,[22][23][24], and (iii) martensitic transformation [8,16,22,23,[25][26][27][28][29][30][31].…”

“…This nonlocal correlation functional is based on rigorous physical insight and can be expected to be transferable with the capability to provide robust predictions of materials behavior, free of all experimental input. The vdW-DF-cx applicability is documented for the PE system and it allows us to detail the nature of the molecular movement that is associated with the martensitic phase transformation [21].…”

Semi-flexible polymer engendered aggregation/dispersion of fullerene (C60) nano-particles: An atomistic investigation

“…Atomistic [7][8][9][10][11][12][13][14][15][16][17] and coarse grained (or united atom) molecular dynamics simulations have been developed to study the various multi-scale characteristics of soft materials at various temperature, pressure and solvency conditions. Atomistic molecular dynamic simulation has been widely used for the investigations of various inter-and intra-atomic interactions between atoms of polymer [7][8][9][10][11][12], DNA [13], dendrimers [14][15][16][17] and its effect over the transformations between globules to extended structure. Benyamini et al [54] has investigated various interactions between fullerene and various proteins using docking and binding site alignment using atomistic model.…”