Chemistry Reference
In-Depth Information
(5)
The
varlet algorithm
is probably the most widely used method. It uses the
positions and accelerations at time
t
, and the positions from the previous
step
(t-δ)
to calculate the new positions at
(t+δt)
, so:
(6)
(7)
(8)
The velocities at time
t
and can be, respectively estimated.
(9)
(10)
The advantages of this method are
time-reversible
and
good energy
conservation
properties, where disadvantage is
low memory storage
be-
cause the velocities are not included in the time integration. However, re-
moving the velocity from the integration introduces numerical inaccura-
cies method, namely the
velocity Verlet
and
Verlet leap-frog algorithms
as
mentioned before, which clearly involve the velocity in the time evolution
of the atomic coordinates.
9.2.1.3
MONTE CARLO
Monte Carlo technique (
Metropolis
method) use random number from
a given probability distribution to generate a sample population of the sys-
tem from which one can calculate the properties of interest. a MC simula-
tion usually consists of three typical steps:
