# Visualizing HP Trajectories in VMD¶

Output from HPlattice simulations can be easily viewed using the VMD molecular graphics program <http://www.ks.uiuc.edu/Research/vmd/>. HPlattice trajectories are saved as xyz coordinate files, which can be loaded by VMD.

To facilitate visualization of the lattice models, HPlattice includes a .vmdrc file. If you copy this file to your home directory and save it as .vmdrc, then VMD should automatically apply the styles to any HPlattice .xyz trajectories that you load from the command line.

To call VMD from the command line, create a link to the VMD binary. On a mac, the command would be:

ln -s /Applications/VMD\ 1.9.1.app/Contents/vmd/vmd_MACOSXX86 /usr/local/bin/vmd


Then, if the .vmdrc file is in your home directory, this command would open an HPlattice trajectory in VMD and apply the HPlattice style by default:

vmd trajectory.xyz


Which should produce a chain that looks like this:

Sometimes VMD draws the topology of the chain incorrectly. In that case, the easiest way to correct it is to enter these commands on the Tk console:

topo getbondlist
topo setbondlist {{0 1} {1 2} {2 3} {3 4} {4 5} {5 6} {6 7} {7 8} {8 9}}


You’ll need to adjust the second command to match the length of your chain. The last pair should be {N-2 N-1}, where N is the length of the chain.