Submonolayer molecular hydrogen on graphite

A path-integral Monte Carlo study

Kwangsik Nho, Efstratios Manousakis

Research output: Contribution to journalArticle

17 Citations (Scopus)

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 ρ0 = 0.0705 Å-2. We also determine that the first layer promotion coverage is at 0.094 Å-2 in agreement with experiment. Second we introduce the full H2-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 √3×√3 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 languageEnglish (US)
Article number115409
Pages (from-to)1154091-11540912
Number of pages10386822
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume65
Issue number11
StatePublished - Mar 15 2002
Externally publishedYes

Fingerprint

Graphite
Hydrogen
graphite
hydrogen
solid phases
vapor phases
Substrates
Vapors
fluids
promotion
Fluids
plots
distribution functions
Probability distributions
specific heat
Specific heat
Vacancies
interactions
Distribution functions
vapors

ASJC Scopus subject areas

  • 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, 115409, 15.03.2002, p. 1154091-11540912.

Research output: Contribution to journalArticle

@article{7ef51f8ef2ce4ba588049170dd32c382,
title = "Submonolayer molecular hydrogen on graphite: A path-integral Monte Carlo study",
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 ρ0 = 0.0705 {\AA}-2. We also determine that the first layer promotion coverage is at 0.094 {\AA}-2 in agreement with experiment. Second we introduce the full H2-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 √3×√3 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.",
author = "Kwangsik Nho and Efstratios Manousakis",
year = "2002",
month = "3",
day = "15",
language = "English (US)",
volume = "65",
pages = "1154091--11540912",
journal = "Physical Review B-Condensed Matter",
issn = "0163-1829",
publisher = "American Institute of Physics Publising LLC",
number = "11",

}

TY - JOUR

T1 - Submonolayer molecular hydrogen on graphite

T2 - A path-integral Monte Carlo study

AU - Nho, Kwangsik

AU - Manousakis, Efstratios

PY - 2002/3/15

Y1 - 2002/3/15

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 ρ0 = 0.0705 Å-2. We also determine that the first layer promotion coverage is at 0.094 Å-2 in agreement with experiment. Second we introduce the full H2-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 √3×√3 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 ρ0 = 0.0705 Å-2. We also determine that the first layer promotion coverage is at 0.094 Å-2 in agreement with experiment. Second we introduce the full H2-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 √3×√3 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.

UR - http://www.scopus.com/inward/record.url?scp=0037087895&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0037087895&partnerID=8YFLogxK

M3 - Article

VL - 65

SP - 1154091

EP - 11540912

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 0163-1829

IS - 11

M1 - 115409

ER -