Computer simulation studies of a square-well fluid in a slit pore. Spreading pressure and vapor-liquid phase equilibria using the virtual-parameter-variation method J. Chem. Phys. 112, 5168 (2000) Vapor-liquid phase equilibria of square-well ͑SW͒ fluids of variable interaction range: = 1.25, 1.75, 2.0, and 3.0 in hard slit pores are studied by means of grand-canonical transition-matrix Monte Carlo ͑GC-TMMC͒ simulation. Critical density under confinement shows an oscillatory behavior as slit width, H, reduced from 12 to 1 . Two linear regimes are found for the shift in the critical temperature with the inverse in the slit width. The first regime is seen for H Ͼ 2.0 with linear increase in the slope of shift in the critical temperature against inverse slit width with increasing interaction range. Subsequent decrease in H has little consequence on the critical temperature and it remains almost constant. Vapor-liquid surface tensions of SW fluids of variable well extent in a planar slit pore of variable slit width are also reported. GC-TMMC results are compared with that from slab based canonical Monte Carlo and molecular dynamics techniques and found to be in good agreement. Although, vapor-liquid surface tension under confinement is found to be lower than the bulk surface tension, the behavior of surface tension as a function of temperature is invariant with the variable pore size. Interfacial width, , calculated using a hyperbolic function increases with decreasing slit width at a given temperature, which is contrary to what is being observed recently for cylindrical pores. Inverse scaled interfacial width ͑ / H͒, however, linearly increases with increase in the scaled temperature ͑T c,bulk − T͒ / T c,bulk .

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