• Bugfix: On restart warning message wrongly accused particles of being inside the mesh domain.
• add_vapor_source(“species”, A, B) → Pressure source with
• Memory bug with temperature distribution file fixed.

• Bugfix: Program execution could freeze on restart with changed quad structure.
• Bugfix: Program execution could freeze for setups with lots of empty quads, i.e. quads inside mesh domain.
• New feature: 'POSITION'-plots for particle energy at absolute coordinates. Should be used with limited amount of particles only.
• Improvement: Load balancing aligned for gas flow and plasma simulation. Load time of field computation is measured for the latter. The load optimization algorithm now uses the average load per node instead of load per quad. However, communication load is still a non-sophisticated guess in load balancing algorithm.
• Bugfix: Removed a script relict regarding 'PAR.BB_adjust' in 'init_fieldsolver.r'.

• E-field solver #1: Improvements to make it more robust and reliable.
• E-field solver #2: Overhaul of convergence computation allows for much faster RF simulations.
• E-field solver #3: Removed damping scheme as it yields artificial cooling.
• Sub-cycling #1: Factor for ions reduced to 0.1 x sqrt(mass heaviest ion / mass electron) due to noise and artificial cooling issues.
• Sub-cycling #2: Separate sub-cycling interval for neutrals with a factor of 10.0 x sqrt(mass heaviest neutral / mass electron).
• Collision cycle: Replaced “one-takes-it-all” with “equal-share” electron energy partitioning model which seems to be PIC-MC modeling consensus.
• Scripts: Bug-fixes and improvments to multi-quad feature.
• Scripts: New function “ReadFromFile_Entry” in sigma.r to compute cross sections from raw data.

• Bugfix: Direction vector for azimuthal angle in angular histograms was overwritten by subsequent histograms.
• Internally:
  • Histogram objects are now stored in a SVector<PICMC_Histogram> structure.
  • struct PICMC_GenericBorder::ELEMENT became a class PICMC_ELEMENT on its own and is now found in Border/Element.cxx, Border/Element.h
• Bugfix: Automatic correction of element normals in BEM field solver improved.
• Bugfix: “Tunneling” of membrane mesh elements conflicted with specular boundary conditions.
• Bugfix: Major bug concerning issues with mesh planes coninciding with quad interfaces.
• Bugfix: Threshold adjustment due to particle leakage in rare occurances.
• Bugfix: Insufficient accuracy of geometry date in 'xxx_bfield.rd' script.
• Bugfix: Threshold adjustment due to rounding errors in the range of 1e-12.
• Bugfix: Restart failed due to missing 'boundingbox.rd' file (used in load_balance.r).
• Bugfix: Check if floating conductors are separated from non isolator.
• Improved constrain test at start time for use with multi-quad segmentation.
• Improved evaluation check when using conductive mesh areas, i.e. floating potentials.
• Loaded B-Field is checked on consistency with domain settings, i.e. geometry and cell resolution.
• Internally: Removed couple of obsolete variables and code fragments.
• Removed spamming of '.sim' files.

• Bugfix: charge checkpoint → after restart the charges for each quad are now consistent with last step before the checkpoint

• Bugfix: Threshold adjustment in analytical cell surface computation to prevent nullification of “very small” surfaces.
• Bugfix: An array index could have been greater than the array index space. This also solved issues with the new particle data structure and using realloc, respectively.

• New wall reaction model (detailed documentation will follow).
  • Possible wall types will be only “wall” and “membrane”
  • Detailed reaction chemistry at walls can be defined via reaction chains for each wall
  • Particle sources are integrated into new wall model
• Energy histograms are now also produced for neutrals
• The energy range of the histogram can be adjusted species-wise by the HIST_RANGE_Species parameter in the parameter file
• DSMC_Generic_Border::RecomputeCellSurface() replaced by an analytical method leading to faster startup times.
• Bugfix: Particles at membrane borders are now correctly reflected if not transmitted.
• New checkpointing routines for particle data, averages, charges and wall material coverages.
  • Checkpoints can now be loaded separately for single species
  • Restart works even if cell spacing, Quad alignment (→ MultiQuad model) and NREAL_SCALE has been changed
• Due to the new wall model and new checkpointing, version 2.4.0+ is not compatible with computation runs made with versions ⇐ 2.3.7.3

• DSCM / PIC-MC simulation
  • Bugfix in boundingbox.r and boundingbox2.r: Rounding error due to insufficient number of digits.
  • FIM and BEM_UMFPACK including all library dependencies removed.
  • Calls for generic border hit query significantly reduced (> 50%) by using element-LUT (Look-up-Table).

• DSCM / PIC-MC simulation
  • Plot routine: Plot cells with zero volume again. Too much secondary issues with optimization approach.
  • New four digit version tag.
  • Removed “static” variables in Create2DVelocity.cxx due to some compatibility(?) issues.

• DSCM / PIC-MC simulation
  • Performance: Cell volume computation has been slightly accelerated (15%).
  • Bugfix: Electric boundaries at quad interfaces could cause trouble due to node assignment ambiguity between picmc_border.cxx and picmc_quad.cxx.
  • Bugfix: Optimization approach in cell volume computation routine could cause trouble due to inside-check-trajectory started exactly in cell center.
  • Major Bugfix: Error migrated into 2.3.5. as cell index computation has been unified. Regards TEX solver with floating potentials.
  • Plot routine: Skip output for cells with volume = 0.

• BEM solver
  • Tolerance threshold of 1e-10 in angular sum check (must be 4*PI for outer volume) was too low. Reset to 1e-3 which is more reasonable.

• DSCM / PIC-MC simulation
  • Unified cell indexing which caused a lot of confusion.
  • Plot routine: Using proper superscripts.
  • Plot routine: Skip output for cells which are inside mesh volume.
  • Plot routine: New plot tag “position” which prints absolute particle position and energy of ALL(!) particles. Thus, handle with care and only for testing purposes.
  • Bugfix in module_picmc.cxx → plot routine: File handler has not been closed properly.
• Postprocessing
  • module_ppp added which allows for fast postprocessing via RVM scripts. This feature is still experimental and will be further improved.

• DSCM / PIC-MC simulation
  • Initial border solidity changed from 1.0 to 0.5 to speed up convergence with reactive borders.
  • Accurate computation of effective absorption surface, i.e. intersection planes of finite elements with grid cells.
  • Bugfix: Solidity was not correctly loaded messing up simulations with reactive border model on restart.
  • Bugfix: Reaction species (if defined) is generated for all 4 cases with reacitve border model.
  • Bugfix: Threshold for particle-to-cell assignment too coarse causing stripe artifacts in absorption plot.
  • Import of temperature distribution into physical mesh surface, see documentation Border temperature distribution.

• DSMC only:
  • Novel method for defining multiple connected bounding boxes with different segmentation, see documentation MQUAD / MJOIN.

• Parameter files
  • sigma.r: included cross section for higher order ionizations, i.e. e + Ar+ → 2e + Ar++, etc.

• DSCM / PIC-MC simulation
  • Adjusting TEX solver to handle voltage sources on floating potential, i.e. capacitively coupled to a reference (ground) potential.
  • Removed “outlet” border type due to redundancy with “wall” border type.
  • Additional feature for “membrane” border types: Species transformation on transmission, i.e. with “rp” and “sp” defined, transmitted particles are transformed into rp = [“xx”, ..] with a probability sp = [“p”, …].
  • Re-inserted query if particle is inside mesh in ReadDumpFile routine. Wonder, why it has been removed.
  • Minor: Changed boundary condition name PERIODIC to INTERFACE for clarification.

• Parameter files
  • init.r: Additional parameter “.vf_coupling” in border declaration. One has to define name of border which is coupled with this one. Thus, voltage separation between electrodes on a common floating potential can be set up.
  • init.r: Adjustments due to border type “outlet” removed.
  • sigma.r: Duplicated SiH4 cross sections but with SiH3, e.g. SiH4 + SiH4 to SiH3 + SiH4, SiH4 + NH3 to SiH3 + NH3, etc.

• DSMC / PIC-MC simulation
  • Bugfix regarding TEX solver: Further simplification of threshold measurement process. No arbitrary accuracy factor anymore. Instead reference solution with maximum accuracy is computed.
  • Bugfix regarding TEX solver: If computation diverges reiteration takes place but floating potentials have not been reset preventing convergence.
  • Bugfix regarding TEX solver: Catching convergence threshold = 0 on convergence measurement if quad is (temporarily) field free.
  • Bugfix regarding membrane border transmission: “Tunneling” of particle through mesh element was error prone. Now a flag is set to perform a clean move through accordant element.

• DSMC / PICMC simulation
  • Send and receive buffer within MPI wrapper without limitation anymore.
  • Overworked TEX solver:
    • Bugfix: Convergence measurement stopped for bipolar periodic voltages.
    • Bugfix: Convergence threshold and AlphaSOR setting was not feasible for 1D plasma simulation.
    • Convergence measurement now takes into account local value margin and grid dimension.
    • If AlphaSOR is set too high and solver diverges, respectively, reiteration with reduced AlphaSOR is triggered properly now.

• Parameter files
  • AlphaSOR set to 1.60 for 3D, 1.85 for 2D and 1.95 for 1D setups in master.r file.

As seen in the figure below TEX solver results are reliable now for 1D cases with version 2.3.0 and significantly faster for 2D cases. Heavy 3D cases lack any performance gains so far but results are the same.

• DSMC / PICMC simulation
  • Major bugfix regarding membrane border type which could cause simulation to freeze.

• Parameter files
  • Only one output message to inform if magnetic field files are loaded or not.

• Cross section data base
  • Included Ta - Ta and Ta - Ar cross section.

• Implemented logging of PIC-MC runs. All state information gets appended to <parfile>.log.

• DSMC / PICMC simulation
  • Overwork of MPI communication scheme: Dynamic memory allocation for send and receive buffer. Hence, MPI crashes due to insufficient buffer size should be history.
  • Using time averaged charged particle states for charge-neutral collisions in DSMC mode. However, the approach has been tested for a particular parameter setup only (RF-PECVD simulation in H2/SiH4).
  • Neutral particles are initialized randomly again to prevent plasma artifacts in PICMC mode.
  • Bugfix regarding read dumpfile routine.

• Parameter file
  • Automatically generated list of available species in species definition section.

• Cross section database
  • Comprehensive extension regarding O2, H2 and SiH4 plasma chemistry. Validation against experiments are promising that we now have the basic reaction schemes for a-Si:H / µc-Si:H film growth.

• Postprocessing
  • Reasonable names and SI-unit definition in all plots.

• DSMC simulation
  • The membrane border now works as a single surface; the transmission probability now works properly.
  • Membrane borders now can have an absorption probability in order to work as transparent pumps in low-dimensional setups.
• Magnetic field computation
  • The direction of surface normals is now automatically detected
  • Simplified invocation schedule –> initbfield is only required once
• Electric field computation
  • Fixed TEX solver scheme for dielectric boundaries. No divergence issues until now.
  • Temporarily removed algorithm which improves potential sampling at mesh-contours. Too many bugs demand complete overwork.
• Load balancing
  • The load balance algorithm is now aware of the actual distribution of picmc processes on the cluster.
• Postprocessing:
  • Bug in pressure and temperature plot removed
  • rvmlibs/extract.r with simplified interface and improved format of extracted data. A new method get_multi_averages is implemented for that purpose.
  • Electric potential is now being plotted as snapshot and as time averaged plot. The latter can be important e. g. for RF discharges.
• Checkpointing
  • Besides particle coordinates and velocities in dumpfile.bin, also the time averaged values are now stored in tavg_dumpfile.bin. Upon continuation, the so far time-averaged values are re-used.