Highlights of GPT version 3.1: The tracking engine and output generator of GPT version 3.1 is significantly improved compared to version 3.0:

Fast snapshots that produce time-domain output without slowing down the ODE solver
In previous versions, time-domain output had to be generated with the tout keyword. Internally, tout instructs the GPT ODE solver to decrease its stepsizes in such a way that the particle coordinates are calculated exactly at the specified times. The tout algorithm starts to make small adjustments to the stepsizes ahead of the requested output time in order to end correctly. As a result, tout slows down the ODE solver. GPT version 3.1 has a new snapshot command that is completely decoupled from the stepping algorithm. The new snapshot keyword also writes the phase-space coordinates at the specified simulations times, but it does so using high-order interpolation instead of slowing down the ODE solver. For a series of time domain outputs with dense spacing this results in a significant performance increase without any loss in accuracy.
The new snapshot command is particularly useful when the CPU time is dominated by the calculation of the electromagnetic fields and not by the tracking itself, such as is the case in a molecular dynamics simulation of a diffraction experiment.

Perfect screens without interpolation error
Using the same interpolation algorithm as described above, the screens in GPT version 3.1 do not contain interpolation errors. That is to say, the interpolation error is always less than the tracking error. This allows the use of screen output in regions with very high field gradients. Without loss of accuracy it is now possible to position a large number of screens very densely together in a high-field region, even if particles pass several screens during one timestep.


A selection of the common features of GPT is listed below. Please contact us whenever you have any questions about the capabilities of GPT related to your project.

Equations of motion
5th order embedded Runge-Kutta
Adaptive stepsize control
Best accuracy over 10-10
Any number and any type of particles
Additional differential equations
    Windows User Interface*
Fully integrated set-up editor
On-line help
Plots of raw GPT output
Plots of all data-analysis results
Plots of particle trajectories
Multiple synchronized windows
Wizards for custom elements
GPTwin User Interface
Output
At specified simulation times
At 3D planes (nondestructive screens)
Coordinates and electromagnetic fields
Trajectory output
    Space-charge
3D particle-in-cell
3D point-to-point 1)
2D point-to-ray
2D point-to-circle
 
Data-analysis
Fully hierarchical
Standard macroscopic quantities
RMS, 90% and 100% Emittance
Courant-Snyder parameters
Histograms
Color-density plots
Support for files >>4 GB
GPT plotting   Scanning and solving
Automatic parameter scans
Multi-dimension root-finder
Multi-dimensional optimizer
MPI scans over several PC's 2)
Root-finding and solving
      Collector design
Multiple-scattering
plate, pipe, cone, torus, sphere, iris
Current/Power density plots
Collector design
Beam line components
barmagnet, bend, bz, bzsolenoid,
circlecharge, drift, ecyl, erect,
ezcell, linecharge, magline, magplate,
magpoint, multislit, platecharge,
pointcharge, quadrupole, rectcoil,
rmax, sextupole, solenoid, trwcell,
trwlinac, trwlinbm, undueqfo, unduplan,
xymax
Custom elements
    Interfaces with other codes
2D and 3D electrostatic field-maps
2D and 3D magnetostatic field-maps
2D TM cavity field-map
Poisson/ Superfish interface
Tabulated ascii input and output
DXF output for 3D drawing software
SDDS conversion utility
Field import

1) GPT version 3.0 contains a fast O(N log N) point-to-point space charge model. The 2.8 release contains an O(N2) version.
2)
Platform dependant, see the GPT versions page for details.