SPPARKS WWW Site - SPPARKS Documentation - SPPARKS Commands

ecoord command


ecoord N eng 


ecoord 8 5.6
ecoord 0 1.0e20
ecoord * 1.0
ecoord 8*12 10.0 


This command sets the energy of an occupied site in a lattice as a function of coordination number, where coordination = the number of occupied neighbor sites. See the app_style diffusion nonlinear command for how the energy change of the system due to a diffusive hop is used to calculate a probability for the hop to occur.

Typically, Nmax+1 values should be specified by using this command one or more times, with N varying from 0 to Nmax, when Nmax is the number of neighbor sites for each lattice site.

The N index can be specified in one of two ways. An explicit numeric value can be used, as in the 1st example above. Or a wild-card asterisk can be used to set the energy value for multiple coordination numbers. This takes the form "*" or "*n" or "n*" or "m*n". If Nmax = the number of neighbor sites, then an asterisk with no numeric values means all coordination numbers from 0 to Nmax. A leading asterisk means all coordination numbers from 0 to n (inclusive). A trailing asterisk means all coordination numbers from n to Nmax (inclusive). A middle asterisk means all coordination numbers from m to n (inclusive).

Note that if the third example is specfied first, followed by the first example, then the effect would be to set the energy value for all coordination numbers to 1.0, then overwrite the energy value for coordination number 8 to 5.6.

The eng value should be in the energy units defined by the application's Hamiltonian and should be consistent with the units used in any temperature command.


This command can only be used as part of the app_style diffusion nonlinear application.

Related commands:

deposition, barrier


Energy values for all coordination numbers are set to 0.