X.—The methane equilibrium

Xthe Experimentx and Its Design

Some teaching material which invites a group of students to design and carry out a small experiment to investigate the working of short term memory is described. No equipment of any kind is required. These ideas have been found to be very helpful in making students think about some very basic and practical issues in designing and carrying out an experiment. The simple nature of the material mak...

Methane and carbon at equilibrium in source rocks

Methane in source rocks may not exist exclusively as free gas. It could exist in equilibrium with carbon and higher hydrocarbons: CH4 + C < = > Hydrocarbon. Three lines of evidence support this possibility. 1) Shales ingest gas in amounts and selectivities consistent with gas-carbon equilibrium. There is a 50% increase in solid hydrocarbon mass when Fayetteville Shale is exposed to methane (450...

Non-equilibrium Molecular Dynamics Simulation of Dense Fluid Methane

We present a non-equilibrium molecular dynamics simulation of 125 methane molecules using a variant of the isokinetic “sllod” algorithm. The shear viscosity, pressure and internal energy of methane in a dense, supercritical fluid state (temperature 285.7 K and mass density 0.288 g/cm3) are calculated and the viscosity compared with experiment, with excellent agreement: the predicted shear visco...

Long Range Corrections to the Vapor-Liquid Equilibrium and Surface Tension of Methane with NVT Molecular Dynamics Simulations

Towards bulk thermodynamics via non-equilibrium methods: gaseous methane as a case study.

We illustrate how the Jarzynski equality (JE), which is the progenitor of non-equilibrium methods aimed at constructing free energy landscapes for molecular-sized fluctuating systems subjected to steered transformations, can be applied to derive equations of state for bulk systems. The key-step consists of physically framing the computational strategy of "total energy morphing", recently presen...