dorsal/arxiv
View SchemaOrbital-Free Molecular Dynamics Simulations of Melting in Na8 and Na20: Melting in Steps
| Authors | Andres Aguado, Jose M. Lopez, Julio A. Alonso, Malcolm J. Stott |
|---|---|
| Categories | |
| ArXiv ID | physics/9809019 |
| URL | https://arxiv.org/abs/physics/9809019 |
| DOI | 10.1063/1.479899 |
| Journal | J. Chem. Phys. 111 (1999) 6026 |
Abstract
The melting-like transitions of Na8 and Na20 are investigated by ab initio constant energy molecular dynamics simulations, using a variant of the Car-Parrinello method which employs an explicit electronic kinetic energy functional of the density, thus avoiding the use of one-particle orbitals. Several melting indicators are evaluated in order to determine the nature of the various transitions, and compared with other simulations. Both Na8 and Na20 melt over a wide temperature range. For Na8, a transition is observed to begin at approx. 110 K, between a rigid phase and a phase involving isomerizations between the different permutational isomers of the ground state structure. The ``liquid'' phase is completely established at approx. 220 K. For Na20, two transitions are observed: the first, at approx. 110 K, is associated with isomerization transitions between those permutational isomers of the ground state structure which are obtained by interchanging the positions of the surface-like atoms; the second, at approx. 160 K, involves a structural transition from the ground state isomer to a new set of isomers with the surface molten. The cluster is completely ``liquid'' at approx. 220 K.
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"abstract": "The melting-like transitions of Na8 and Na20 are investigated by ab initio\nconstant energy molecular dynamics simulations, using a variant of the\nCar-Parrinello method which employs an explicit electronic kinetic energy\nfunctional of the density, thus avoiding the use of one-particle orbitals.\nSeveral melting indicators are evaluated in order to determine the nature of\nthe various transitions, and compared with other simulations. Both Na8 and Na20\nmelt over a wide temperature range. For Na8, a transition is observed to begin\nat approx. 110 K, between a rigid phase and a phase involving isomerizations\nbetween the different permutational isomers of the ground state structure. The\n``liquid\u0027\u0027 phase is completely established at approx. 220 K. For Na20, two\ntransitions are observed: the first, at approx. 110 K, is associated with\nisomerization transitions between those permutational isomers of the ground\nstate structure which are obtained by interchanging the positions of the\nsurface-like atoms; the second, at approx. 160 K, involves a structural\ntransition from the ground state isomer to a new set of isomers with the\nsurface molten. The cluster is completely ``liquid\u0027\u0027 at approx. 220 K.",
"arxiv_id": "physics/9809019",
"authors": [
"Andres Aguado",
"Jose M. Lopez",
"Julio A. Alonso",
"Malcolm J. Stott"
],
"categories": [
"physics.atm-clus",
"cond-mat"
],
"doi": "10.1063/1.479899",
"journal_ref": "J. Chem. Phys. 111 (1999) 6026",
"title": "Orbital-Free Molecular Dynamics Simulations of Melting in Na8 and Na20: Melting in Steps",
"url": "https://arxiv.org/abs/physics/9809019"
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