Editing G09 (section)

== BOMD calculations ==

This keyword requests a classical trajectory calculation using a Born-Oppenheimer molecular dynamics model. 

http://www.gaussian.com/g_tech/g_ur/k_bomd.htm

* '''Giving initial velocities''': If you want to give initial velocities, Gaussian is able to generate them providing the energy you want to add into a given normal mode, 
by using the keyword nsample and adding after the coordinates:Mode-num, VibEng(Mode-num), ... for as many modes you wish.
** As example: this will provide an energy of -16.4 kcal/mol to mode 1

 BOMD(Phase=(1,14),RTemp=300,nsample=1,update=12,maxpoints=2,ntraj=10)

 title & charge-multiplicity & coordinates

 0
 1 -16.4

** Please note that in the current version, the sign of the energy is not changing the direction of the velocities generated. So, to change the direction, you will have to run a calculation just to generate the number of velocities you wish ntraj = XX (with maxpoints=2 is very fast). Then take all XX  velocities ''MW Cartesian velocity:'' from the output (remove all text and leave only the three columns of velocities). If the direction is not the desired one change the sign of your velocities (to know it make a test with a small number of steps to each direction). Then read the velocities with the sign changed in a new input after the coordinates (with the NPath on the top and a blank line separating velocities), you will have to use the keyword ReadMWVelocity in the BOMD specifications. You need a set of velocities for each trajectory if not all trajectories will be equal. 

* '''Visualizing BOMD trajectories''': You can visualize each trajectory separately with GaussView. 
** The geometry of your last structure in GaussView does not correspond to the last geometry of your trajectory but to the last geometry found in the output file.
** If the number of steps of your trajectory is very large you might want to kill your GaussView and open it again than wait until GaussView closes your file.