Predicting Crystal Structures: The Parrinello-Rahman Method Revisited (original) (raw)

Structural Phase Transformations via First-Principles Simulation

Europhysics Letters (EPL), 1994

We present a new simulation scheme for structural phase transitions via first principles molecular dynamics. The method is obtained by combining the Car-Parrinello method for ab initio simulation with the Parrinello-Rahman method to account for variable cell shape. We demonstrate the validity of our approach by simulating the spontaneous transformation of silicon from diamond to simple hexagonal phase under high pressure.

Simulation of structural phase transitions by metadynamics

Zeitschrift für Kristallographie, 2000

We describe here in detail the recently introduced methodology for simulation of structural transitions in crystals. The applications of the new scheme are illustrated on various kinds of crystals and the advantages with respect to previous schemes are emphasized. The relevance of the new method for the problem of crystal structure prediction is also discussed.

Structural Phase Trasformations via Ab-Initio Molecular Dynamics

1993

We present a new simulation scheme for structural phase transitions via first principles molecular dynamics. The method is obtained by combining the Car-Parrinello method for ab initio simulation with the Parrinello-Rahman method to account for variable cell shape. We demonstrate the validity of our approach by simulating the spontaneous transformation of silicon from diamond to simple hexagonal phase under high pressure.

First-order displacive structural phase transitions studied by computer simulation

Physical Review B, 1992

We have constructed a lattice-dynamical model which possesses many of the features occurring at first-order structural phase transitions in solids. The model includes an asymmetric nonlinear on-site potential and anharmonic interparticle interactions. The anharmonicity in the interaction is introduced in a way which lowers the phonon frequencies in the high-temperature, metastable phase. The interaction provides a mechanism for a vibrational-entropy-driven first-order phase transition. We present results from molecular-dynamics calculations which show (i) clear evidence in the thermodynamic functions for the existence of a first-order phase transition produced by heating from low temperature, and (ii) unusual properties for the position probability distribution and the dynamic structure factor. These spectral functions have significant intensity in the quasielastic region, and this contribution is strongly maximized near the transition temperature. The wave-vector dependence of this "central peak" clearly points to the existence of propagating nonlinear modes.

Computer simulations of heterogeneous crystal growth of atomic systems

Molecular Physics, 2005

The systematic study of the mechanisms of heterogeneous crystal growth has proven somewhat difficult. Here we briefly review previous work in this area. We then report a novel molecular dynamics simulation methodology that has been developed to enable the creation of steady-state crystal growth-melting. We employ this methodology to examine BCC and FCC 001, 011 and 111 crystal faces of systems of spherical particles interacting through Lennard-Jones and inverse sixth-power potentials. Various growth-melting conditions are explored involving different temperature gradients and velocities. Profile functions of various quantities across the interface have been recorded; as measured in the moving frame by the present approach, these functions are effectively averaged over the molecular detail of the interface and become smooth. This characteristic allows for new ways of interpreting profile functions like the energy and local structural order parameters. We find that when the derivative of these profile functions is taken with respect to the z dimension, we obtain consistent peaks that characterize the freezing-melting interfaces. Consequently, the position and width of an interface are easily identified. The interfacial widths calculated show that it is somewhat dependent on the temperature gradient but no dependence on the growth velocity was observed. The interfacial widths are found to decrease in the order 001 >011 > 111. Furthermore we determine interfacial tensions, which arise directly out of our methodology. We are able to demonstrate that ordering and disordering are distinct and different processes occurring at both the melting and freezing interfaces.

Stability and Structural Transitions in Crystal Lattices

The advance in nanotechnology has lead to necessity to determine strength properties of crystal structures. Stability of a structure under finite deformations is closely connected with its strength. In this work stability of plane triangular (single atomic layer of FCC and HCP) and FCC lattices under finite strain is investigated. Analysis and modeling based on discrete atomistic methods is proposed. The medium is represented by a set of particles which interact by a pair force central potential, e.g. Lennard-Jones and Morse. Direct tensor calculus is used. Dynamic stability criterion is established: frequency of elastic waves is required to be real for any real wave vector. The considered approach allows to describe structural transitions in solids on the base of stability investigation of pre-strained crystal lattices. The results of direct MD simulation do not contradict the results of the calculations.

Molecular dynamics simulations of crystallization under confinement at triple point conditions

The Journal of Chemical Physics, 2003

Molecular dynamics computer simulations of crystallization of a Lennard-Jones system under confinement conditions in the vicinity of the triple point are reported. We calculate the force exerted on a crystal by a melt when it crystallizes. The force due to crystallization is reflected in the disjoining pressure isotherms as a characteristic peak. We find that at conditions of high confinement, i.e., pore thicknesses of ≈1 nm, the disjoining pressure can rise up to ≈108 Pa. We also analyze the dependence of the crystallization under confinement as a function of temperature. Confinement can stabilize the crystal phase at temperatures significantly higher than the melting temperature. For the systems studied in this work, a pore of 1 nm thickness stabilizes the crystal phase at temperatures up to 45% higher than the normal melting temperature. In addition we consider the disjoining pressure profile along confining pore slits of finite lengths. The finite size effects due to the pore le...

New techniques for simulating crystals

Molecular Simulation, 2009

Methods for simulating solid crystalline phases are generally not as straightforward as those for fluids. This work discusses the reason for this and reviews some recently developed Monte-Carlo techniques for simulating crystalline phases. The self-referential method for calculating crystal free energies is described first. This technique is particularly straightforward and it is expected to be very versatile. Next, a novel kind of Gibbs ensemble method adapted to treat crystalline solid-fluid coexistence is described. This technique requires free energy calculations of the crystalline phase as input, and of course these can be provided by the SR method.