Actions

From PIMC++

PIMC++ supports a number of Actions that can be turned on and off throughout the simulation.

PIMC++ samples the stationary distribution

where S is the action.

A typical simulation of PIMC++ uses a Kinetic Action, a Potential Action (usually a pair action of some sort) and possibly a nodal action.

Other actions may be used through the code that are not being sampled in the stationary distribution but are being used in some other manner. For example, an action might be used at a higher level in a multistage move to approximate the higher levels.

A typical run of PIMC++ requires certain paramaters set. These paramaters are set in the Actions section (At some point I think we would like to have hiearchal sections for kinetic action, potential action, etc.)

Kinetic Action Paramaters: NumImages: The kinetic action formally is

where k,k' index's the k,k' image of particle i,j. This paramater defines whether the sum is only over images in the first box (=0), the nearest 27 boxes (=1), etc. Typically this can be 0 unless

is on the order of the box size. Potential Action Paramaters: Array<string,1> PairActionFiles(numPairActions): Specifies the PairActionFiles. The full path must be given to these files. The PairAction files that can be used in PIMC++ include those from squarer++ and those from David Ceperely's squarer. To use the latter requires writing a PairAction file that wraps the dm files from this squarer. See below for a description to accomplish this. MaxLevels: Specifies the total number of levels that are read in from the density matrix file. This must be less then (or equal to) the total number of levels in teh density matrix. It also must be more then the number of levels that you are using in bisection (which is why more then onle level is read in). The highest level that is read in is the value of tau tbeing used. Wrapping David Ceperley's squarer dm files in a PairAction files such that they can be used.

(details to come)