  A newly developed fast molecular-dynamics method is applied to BaTiO3
ferroelectric thin-film capacitors with short-circuited electrodes or under
applied voltage. The molecular-dynamics simulations based on a first-principles
effective Hamiltonian clarify that dead layers (or passive layers) between
ferroelectrics and electrodes markedly affect the properties of capacitors, and
predict that the system is unable to hop between a uniformly polarized
ferroelectric structure and a striped ferroelectric domain structure at low
temperatures. Simulations of hysteresis loops of thin-film capacitors are also
performed, and their dependence on film thickness, epitaxial constraints, and
electrodes are discussed.
