Chemistry Reference
In-Depth Information
Figure 5
Power spectrum analysis of the Langevin dynamics simulation of the model
system. Frequency peaks are in qualitative agreement with constant-energy simulations
but somewhat broadened when compared with the data shown in Figure 2.
As pointed out earlier and shown in Figure 4, the energy of the bonded
terms is an especially sensitive detector of instability arising from MTS reso-
nance artifacts. Because the total energy is not constant in Langevin simula-
tions, bond energy can be used to monitor the stability of a Langevin
trajectory. Figure 6 shows that the energy behavior of the Langevin-stabilized
0.48
Full Period
0.47
Half-Period
0.46
0.45
0.44
0
5
10
15
Slow Force Update Interval (fs)
Figure 6
Average bond energy as a function of slow force update interval for a
Langevin-stabilized extrapolation MTS method. These average energies, taken from
long simulations, do not exhibit the sensitivity to the slow force update interval seen
with impulse MTS methods in Figure 4.
