溶剂层上加真空层，如何确定溶剂层的密度变化

cxw-suzy

各位老师，麻烦请教一下，我用的material studio，建立了溶质层,溶剂层，溶剂层上面加了真空层，然后跑nvt，如下图所示：
，现在审稿人针对我加的真空层提出质疑，审稿意见如下：

The authors introduce vacuum to avoidboundary effects associated with periodic boundary conditions. This choice isat risk of introducing artefacts in the simulations since the density profileof the solvent will be affected by the presence of the vacuum.

For the calculations to be valid the solventmust equilibrate to the correct bulk density away from the crystal solution andthe solvent vacuum interface for the entire duration of the production run usedto sample the interface structure.
请问他这是什么意思，我改如何回复或者操作？

cxw-suzy

@sobereva 尊敬的管理员老师，您知道这是啥意思吗？