Abstract
It has been recently conjectured that bridge functions remain nearly invariant along phase diagram lines of constant excess entropy for the broad class of R-simple liquids. To test this hypothesis, the bridge functions of Yukawa systems are computed outside the correlation void with the Ornstein-Zernike inversion method employing structural input from ultra-accurate molecular dynamics simulations and inside the correlation void with the cavity distribution method employing structural input from ultra-long specially designed molecular dynamics simulations featuring a tagged particle pair. Yukawa bridge functions are revealed to be isomorph invariant to a very high degree. The observed invariance is not exact, however, since isomorphic deviations exceed the overall uncertainties.
Highlights
One of the fundamental problems in the statistical mechanics of liquids concerns the accurate computation of static pair correlations with the knowledge of the pair interaction potential alone and without resorting to computer simulations
Bridge functions of dense Yukawa liquids were systematically computed aiming to confirm or disprove the validity of the conjecture of reduced unit bridge function invariance along isomorphs, i.e., phase diagram lines of constant excess entropy. 16 state points were selected that belong to four isomorphs and cover the entire dense liquid Yukawa one-component plasmasYukawa one-component plasma (YOCP) phase diagram up to the vicinity of the liquid– solid phase transition
Intermediate and long range bridge functions were made accessible after application of the Ornstein–Zernike inversion method with radial distribution function input from ultra-accurate standard canonical molecular dynamics simulations that employed carefully selected parameters, while short range bridge functions were made accessible after application of the cavity distribution method with structural input from ultra-long specially designed canonical molecular dynamics simulations featuring a tagged particle pair
Summary
One of the fundamental problems in the statistical mechanics of liquids concerns the accurate computation of static pair correlations with the knowledge of the pair interaction potential alone and without resorting to computer simulations. A novel integral equation theory approach has been formulated that is based on the conjecture that bridge functions remain invariant along phase diagram lines of constant excess entropy for a broad class of liquids known as R-simple.. A novel integral equation theory approach has been formulated that is based on the conjecture that bridge functions remain invariant along phase diagram lines of constant excess entropy for a broad class of liquids known as R-simple.27 It has been coined as isomorph-based empirically modified hypernetted-chain (IEMHNC) and has been applied to Yukawa and bi-Yukawa liquids resulting in a remarkable agreement with simulations..
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