Structural part of ucf file

[Namkyu Kim]

Hello,

I have two quetions about coding for Vampire.

First, you said that there is structural part of ufc file for customized simulation system. 

So, how can I compose the structural part of ufc file and use how(what command for importing structural ucf file)?

Second question is about the putting certain initial state for simulation.

For example, the field cooling is needed before hysteresis loop simulation to calculate for exchange bias.

Can I compose the code for succesive simulation (field coolind -> hysetresis loop) or put the certain state for inital state(eg. by using cfg file) in the simulation?

Thank you !!

[richard....@gmail.com]

Dear Namkyu Kim,

The draft UCF file format (attached) includes all the structural and interaction information for the simulation, so you need to define these (by the way the sign convention in the spec is wrong, +ve is ferromagnetic). This is best done with a code which can calculate all the interactions (for example neighbors and their interaction strength). I would like to generalize this a little better so that there is a simple utility that will do this directly, but for the moment there is an example code in the VAMPIRE source code (unit-cell-creator.cpp) which generates an example ucf file. Once you have that you can read it into the input file using

material:unit-cell-file=file.ucf

For doing a sequence of simulations (and saving the spin configurations) you need to use the last version of the code (develop branch on github) which has support for checkpointing. In the first simulation you can specify:

sim:save-checkpoint=end # this saves a checkpoint of all the spins at the end of the simulation 

In the next program you can load this in using

sim:load-checkpoint=restart # load in an existing checkpoint and restart the simulation

The checkpoints are stored as .chk files, which works in parallel but it is essential that the same number of CPUs is used for all segments. Also, it is usually best to run each segment in a new folder, so that you can keep the different spin configurations after each part.

All the best,

Richard