Abstract
We have used path-integral Monte Carlo (PIMC) to simulate molecular hydrogen on graphite at submonolayer coverage. First we use a flat substrate and we study the first layer for various values of the coverage up to layer completion. We found that the first layer has a solid-gas coexistence phase at low densities and a triangular solid phase at and above the equilibrium density (formula presented) We also determine that the first layer promotion coverage is at (formula presented) in agreement with experiment. Second we introduce the full (formula presented)-graphite interaction, i.e., we include the effects of substrate corrugations. In this case we carry our PIMC simulations on a variety of systems at and below the 1/3 coverage. We calculate the energy as a function of coverage, contour plots of the molecule probability distribution, the pair distribution function, the static structure function and the specific heat. When the substrate corrugation part of the interaction is included we find that at 1/3 coverage the system is in a (formula presented) commensurate solid phase. At coverages below that and at low enough temperature the system exists in solid clusters surrounded by vapor. At coverages below a critical density, defining a tricrical point, as the system is heated up these clusters melt into a uniform fluid phase. We find that below the commensurate density and above the tricritical point, as the clusters are heated up, first they undergo a transition into a phase where the vapor phase disappears and a commensurate phase with vacancies arises. This commensurate solid melts at higher temperature into a uniform fluid phase.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1-12 |
| Number of pages | 12 |
| Journal | Physical Review B - Condensed Matter and Materials Physics |
| Volume | 65 |
| Issue number | 11 |
| DOIs | |
| State | Published - Jan 1 2002 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
Cite this
Submonolayer molecular hydrogen on graphite : A path-integral Monte Carlo study. / Nho, Kwangsik; Manousakis, Efstratios.
In: Physical Review B - Condensed Matter and Materials Physics, Vol. 65, No. 11, 01.01.2002, p. 1-12.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Submonolayer molecular hydrogen on graphite
T2 - A path-integral Monte Carlo study
AU - Nho, Kwangsik
AU - Manousakis, Efstratios
PY - 2002/1/1
Y1 - 2002/1/1
N2 - We have used path-integral Monte Carlo (PIMC) to simulate molecular hydrogen on graphite at submonolayer coverage. First we use a flat substrate and we study the first layer for various values of the coverage up to layer completion. We found that the first layer has a solid-gas coexistence phase at low densities and a triangular solid phase at and above the equilibrium density (formula presented) We also determine that the first layer promotion coverage is at (formula presented) in agreement with experiment. Second we introduce the full (formula presented)-graphite interaction, i.e., we include the effects of substrate corrugations. In this case we carry our PIMC simulations on a variety of systems at and below the 1/3 coverage. We calculate the energy as a function of coverage, contour plots of the molecule probability distribution, the pair distribution function, the static structure function and the specific heat. When the substrate corrugation part of the interaction is included we find that at 1/3 coverage the system is in a (formula presented) commensurate solid phase. At coverages below that and at low enough temperature the system exists in solid clusters surrounded by vapor. At coverages below a critical density, defining a tricrical point, as the system is heated up these clusters melt into a uniform fluid phase. We find that below the commensurate density and above the tricritical point, as the clusters are heated up, first they undergo a transition into a phase where the vapor phase disappears and a commensurate phase with vacancies arises. This commensurate solid melts at higher temperature into a uniform fluid phase.
AB - We have used path-integral Monte Carlo (PIMC) to simulate molecular hydrogen on graphite at submonolayer coverage. First we use a flat substrate and we study the first layer for various values of the coverage up to layer completion. We found that the first layer has a solid-gas coexistence phase at low densities and a triangular solid phase at and above the equilibrium density (formula presented) We also determine that the first layer promotion coverage is at (formula presented) in agreement with experiment. Second we introduce the full (formula presented)-graphite interaction, i.e., we include the effects of substrate corrugations. In this case we carry our PIMC simulations on a variety of systems at and below the 1/3 coverage. We calculate the energy as a function of coverage, contour plots of the molecule probability distribution, the pair distribution function, the static structure function and the specific heat. When the substrate corrugation part of the interaction is included we find that at 1/3 coverage the system is in a (formula presented) commensurate solid phase. At coverages below that and at low enough temperature the system exists in solid clusters surrounded by vapor. At coverages below a critical density, defining a tricrical point, as the system is heated up these clusters melt into a uniform fluid phase. We find that below the commensurate density and above the tricritical point, as the clusters are heated up, first they undergo a transition into a phase where the vapor phase disappears and a commensurate phase with vacancies arises. This commensurate solid melts at higher temperature into a uniform fluid phase.
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U2 - 10.1103/PhysRevB.65.115409
DO - 10.1103/PhysRevB.65.115409
M3 - Article
AN - SCOPUS:84878019406
VL - 65
SP - 1
EP - 12
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 0163-1829
IS - 11
ER -