Three-arm ABC Star Copolymer (starABC.pre)

Keywords:

copolymer, multiblock, star

Problem description

This simulation can be performed with a PSimBase license.

This example demonstrates a 3-arm star model in which each arm consists of a different monomer.

Input File Features

Files: starABC.pre.

The variables in the Setup tab are

  • NX (Number of cells in the x-dir)
  • NY (Number of cells in the y-dir)
  • NZ (Number of cells in the z-dir)
  • fA (Length fraction of ‘A’ arm)
  • fB (Length fraction of ‘B’ arm)
  • fC (Length fraction of ‘C’ arm)
  • chiN_SC (Flory \(\chi N\) parameter between the ‘S’ and ‘C’ arms)
  • chiN_EC (Flory \(\chi N\) parameter between the ‘E’ and ‘C’ arms)
  • chiN_SE (Flory \(\chi N\) parameter between the ‘E’ and ‘S’ arms)

This input file illustrates how to setup a copolymer with branch points where more than two blocks are joined

<Block blockA>
  kind = flexPseudoSpec
  scfield = totStyrDens
  ds = DS
  lengthfrac = fA
  headjoined = [freeEnd]
  tailjoined = [blockB blockC]
</Block>

Here the ref:tailjoined parameter has more than one block name listed since the ‘tail’ end is located at the 3-arm star junction point.

Creating the run space

The 3-arm ABC Star Copolymer example is accessed from within PSimComposer by the following actions:

  • Select the New from Template menu item in the File menu.
  • In the resulting New from Template window, select PSimBase and then press the arrow button to the left.
  • Select “Three-arm ABC Star Copolymer” and press the Choose button.
  • In the resulting dialog, press the Save button to create a copy of this example in your run area.

The basic variables of this problem should now be settable in text boxes in the right pane of the “Setup” window, as shown in Fig. 75.

../../../_images/starABCSetupWin.png

Figure 75: Setup window for the Three-arm ABC Star Copolymer example.

Running the simulation

After performing the above actions, continue as follows:

  • Press the Save And Setup button in the upper right corner.
  • Proceed to the run window as instructed by pressing the Run button in the left column of buttons.
  • Note: because the initial random state depends on the number of processors, the final simulation state can depend on the number of processors chosen if running in parallel. The results in this example are produced by running on two processors. The parallel run options can be accessed by going to the ‘MPI’ tab on the left side of the Run button window.
  • To run the file, click on the Run button in the upper right corner. of the window. You will see the output of the run in the right pane. The run has completed when you see the output, “Engine completed successfully.” This is shown in Fig. 76.
../../../_images/starABCRunWin.png

Figure 76: The Run window at the end of execution.

Visualizing the results

After performing the above actions, continue as follows:

  • Proceed to the Visualize window as instructed by pressing the Visualize button in the left column of buttons.
  • Press the “Open” button to begin visualizing.
  • Go to the Scalar Data Variable in the CONTROLS panel on the left and press the arrow to the left
  • Check one of the MonomerDensity boxes (try the totCarbDens database). This selects all of the datafiles for this physical field ‘totCarbDens’. This first *h5 file will be shown first.
  • Move the Dump slider at the bottom of the window to the last position to see the final simulation state.
../../../_images/starABCVizWin.png

Figure 77: Visualization of short name as a color contour plot.

Further Experiments

Change the sizes of the blocks and the interaction parameters and explore this large parameter space.