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Grid/lib/qcd/hmc/UsingHMC.md
2016-10-19 10:51:13 +01:00

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Using HMC in Grid version 0.5.1
These are the instructions to use the Generalised HMC on Grid version 0.5.1.
Disclaimer: GRID is still under active development so any information here can be changed in future releases.
Command line options
===================
(relevant file GenericHMCrunner.h)
The initial configuration can be changed at the command line using
--StartType <your choice>
valid choices, one among these
HotStart, ColdStart, TepidStart, CheckpointStart
default: HotStart
example
./My_hmc_exec --StartType HotStart
The CheckpointStart option uses the prefix for the configurations and rng seed files defined in your executable and the initial configuration is specified by
--StartTrajectory <integer>
default: 0
The number of trajectories for a specific run are specified at command line by
--Trajectories <integer>
default: 1
The number of thermalization steps (i.e. steps when the Metropolis acceptance check is turned off) is specified by
--Thermalizations <integer>
default: 10
Any other parameter is defined in the source for the executable.
HMC controls
===========
The lines
std::vector<int> SerSeed({1, 2, 3, 4, 5});
std::vector<int> ParSeed({6, 7, 8, 9, 10});
define the seeds for the serial and the parallel RNG.
The line
TheHMC.MDparameters.set(20, 1.0);// MDsteps, traj length
declares the number of molecular dynamics steps and the total trajectory length.
Actions
======
Action names are defined in the file
lib/qcd/Actions.h
Gauge actions list:
WilsonGaugeActionR;
WilsonGaugeActionF;
WilsonGaugeActionD;
PlaqPlusRectangleActionR;
PlaqPlusRectangleActionF;
PlaqPlusRectangleActionD;
IwasakiGaugeActionR;
IwasakiGaugeActionF;
IwasakiGaugeActionD;
SymanzikGaugeActionR;
SymanzikGaugeActionF;
SymanzikGaugeActionD;
ConjugateWilsonGaugeActionR;
ConjugateWilsonGaugeActionF;
ConjugateWilsonGaugeActionD;
ConjugatePlaqPlusRectangleActionR;
ConjugatePlaqPlusRectangleActionF;
ConjugatePlaqPlusRectangleActionD;
ConjugateIwasakiGaugeActionR;
ConjugateIwasakiGaugeActionF;
ConjugateIwasakiGaugeActionD;
ConjugateSymanzikGaugeActionR;
ConjugateSymanzikGaugeActionF;
ConjugateSymanzikGaugeActionD;
ScalarActionR;
ScalarActionF;
ScalarActionD;
each of these action accept one single parameter at creation time (beta).
Example for creating a Symanzik action with beta=4.0
SymanzikGaugeActionR(4.0)
The suffixes R,F,D in the action names refer to the Real
(the precision is defined at compile time by the --enable-precision flag in the configure),
Float and Double, that force the precision of the action to be 32, 64 bit respectively.