Pressure Profile Calculation with Mesh Ewald Methods

Abstract

The importance of calculating pressure profiles across liquid interfaces is increasingly gaining recognition, and efficient methods for the calculation of long-range contributions are fundamental in addressing systems with a large number of charges. Here, we show how to compute the local pressure contribution for mesh-based Ewald methods, retaining the typical N log N scaling as a function of the lattice nodes N . This is a considerable improvement on existing methods, which include approximating the electrostatic contribution using a large cut-off and the, much slower, Ewald calculation. As an application, we calculate the contribution to the pressure profile across the water/vapour interface, coming from different molecular layers, both including and removing the effect of thermal capillary waves. We compare the total pressure profile with the one obtained using the cutoff approximation for the calculation of the stresses, showing that the stress distribution obtained by the Harasima and Irving-Kirkwood are quite similar and shifted with respect to each other at most 0.05 nm.

Role of the Counterions in the Surface Tension of Aqueous Surfactant Solutions. A Computer Simulation Study of Alkali Dodecyl Sulfate Systems

“…The simulations were performed using an in-house modified version [76] of the GROMACS 5.1 package [77], which allowed us to calculate the lateral pressure contribution of the individual atoms and hence also the lateral pressure profile as well as the contributions of the various molecules and moieties to it. These lateral pressure contributions, including the terms corresponding to the sPME correction of the electrostatic interaction, were calculated employing the Harasima path as described in our previous publication [78]. We recall here that using the Harasima path allows us to account for the lateral pressure contribution corresponding to the sPME correction [69], and it enables us to distribute the lateral pressure contributions among the individual atoms [57].…”

Calcium ions promote membrane fusion by forming negative-curvature inducing clusters on specific anionic lipids

“…We used the Roux calcium ions [66] with NBFIX corrections [67] as well as the scaled ECCR calcium [68] ions for comparison. Lateral pressure calculations use a modified version of the Sega code [40], that incorporates a Goetz-Lipowsky [69] force decomposition. Membrane shape optimization used a spline-based finite element approach.…”

“…In order to obtain the correct pressure contribution from the ionic double layer, we compute the stress tensor using particle mesh Ewald summation. [40,41] This step is required to account for the extremely long range virial contributions of the charged ion layers (see Methods, and for further discussion see the SI). Spontaneous monolayer curvatures obtained from Eq.…”

Laterális nyomásprofil számításával összefüggõ problémák vizsgálata számítógépes szimulációval

“…Sonne és munkatársai ugyan megmutatták, hogyan lehet az Ewald összegzésbõl származó nyomásjárulékot kiszámítani, 10 [15][16][17][18][19][20] Megmutattuk azonban, hogy az alkalmazott potenciál ilyetén megváltoztatása a szimuláció és az analízis között akár több száz bar rendszeres hibát is okozhat a számított nyomásprofilban. 21 E probléma elkerülésének érdekében megmutattuk, hogyan számítható ki és lokalizálható az elektrosztatikus kölcsönhatás hosszútávú korrekciójának laterális nyomáshoz adott járuléka az sPME módszer 14 alkalmazása mellett. 21 1.…”

“…21 E probléma elkerülésének érdekében megmutattuk, hogyan számítható ki és lokalizálható az elektrosztatikus kölcsönhatás hosszútávú korrekciójának laterális nyomáshoz adott járuléka az sPME módszer 14 alkalmazása mellett. 21 1. Ábra.…”