From cef4ee7026b4eca15efe8cc97a8e603601060b35 Mon Sep 17 00:00:00 2001 From: Gareth Tribello <gareth.tribello@gmail.com> Date: Sun, 24 Jul 2016 16:03:45 +0100 Subject: [PATCH] Fixes to manual for FCCUBIC and SIMPLECUBIC [makedoc] --- src/crystallization/Fccubic.cpp | 3 ++- src/crystallization/SimpleCubic.cpp | 16 ++++++++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/src/crystallization/Fccubic.cpp b/src/crystallization/Fccubic.cpp index 6ea0ce862..cf27beaf1 100644 --- a/src/crystallization/Fccubic.cpp +++ b/src/crystallization/Fccubic.cpp @@ -45,7 +45,8 @@ s_i = \frac{ \sum_{i \ne j} \sigma(r_{ij}) \left\{ a\left[ \frac{(x_{ij}y_{ij})^ In this expression \f$x_{ij}\f$, \f$y_{ij}\f$ and \f$z_{ij}\f$ are the \f$x\f$, \f$y\f$ and \f$z\f$ components of the vector connecting atom \f$i\f$ to atom \f$j\f$ and \f$r_{ij}\f$ is the magnitude of this vector. \f$\sigma(r_{ij})\f$ is a \ref switchingfunction that acts on the distance between -atom \f$i\f$ and atom \f$j\f$ and its inclusion in the numerator and the denominator of the above expression ensures that we are calculating an average +atom \f$i\f$ and atom \f$j\f$ and its inclusion in the numerator and the denominator of the above expression as well as the fact that we are summing +over all of the other atoms in the system ensures that we are calculating an average of the function of \f$x_{ij}\f$, \f$y_{ij}\f$ and \f$z_{ij}\f$ for the atoms in the first coordination sphere around atom \f$i\f$. Lastly, \f$\alpha\f$ is a parameter that can be set by the user, which by default is equal to three. The values of \f$a\f$ and \f$b\f$ are calculated from \f$\alpha\f$ using: diff --git a/src/crystallization/SimpleCubic.cpp b/src/crystallization/SimpleCubic.cpp index dade67033..1b6787ff9 100644 --- a/src/crystallization/SimpleCubic.cpp +++ b/src/crystallization/SimpleCubic.cpp @@ -35,6 +35,22 @@ namespace crystallization{ Calculate whether or not the coordination spheres of atoms are arranged as they would be in a simple cubic structure. +We can measure how similar the environment around atom $i$ is to a simple cubic structure is by evaluating +the following quantity: + +\f[ +s_i = \frac{ \sum_{i \ne j} \sigma(r_{ij}) \left[ \frac{ x_{ij}^4 + y_{ij}^4 + z_{ij}^4 }{r_{ij}^4} \right] }{ \sum_{i \ne j} \sigma(r_{ij}) } +\f] + +In this expression \f$x_{ij}\f$, \f$y_{ij}\f$ and \f$z_{ij}\f$ are the \f$x\f$, \f$y\f$ and \f$z\f$ components of the vector connecting atom \f$i\f$ to +atom \f$j\f$ and \f$r_{ij}\f$ is the magnitude of this vector. \f$\sigma(r_{ij})\f$ is a \ref switchingfunction that acts on the distance between atom \f$i\f$ and atom \f$j\f$ and its inclusion in the numerator and the denominator of the above expression as well as the fact that we are summing +over all of the other atoms in the system ensures that we are calculating an average +of the function of \f$x_{ij}\f$, \f$y_{ij}\f$ and \f$z_{ij}\f$ for the atoms in the first coordination sphere around atom \f$i\f$. +This quantity is once again a multicolvar so you can compute it for multiple atoms using a single PLUMED action and then compute +the average value for the atoms in your system, the number of atoms that have an \f$s_i\f$ value that is more that some target and +so on. Notice also that you can rotate the reference frame if you are using a non-standard unit cell. + + \par Examples The following input tells plumed to calculate the simple cubic parameter for the atoms 1-100 with themselves. -- GitLab