Chemistry Reference
In-Depth Information
lifetime of the catalyst. Dense millimeter tall nanotube
forests
, aligned
normal to the substrate, were created. The
forests
expansion rate could be
extracted, as:
(46)
where, β is the initial expansion rate andis the characteristic catalyst life-
time.
9.4
SIMULATION OF CNT'S MECHANICAL PROPERTIES
9.4.1 MODELING TECHNIQUES
The theoretical efforts in simulation of CNT mechanical properties can be
categorized in three groups as follow:
• atomistic simulation;
• continuum simulation;
• nano-scale continuum modeling.
9.4.1.1
ATOMISTIC SIMULATION
Based on interactive forces and boundary conditions, atomistic model-
ing predicts the positions of atoms. Atomistic modeling techniques can
be classified into three main categories, namely the MD, MC and Ab ini-
tio approaches. Other atomistic modeling techniques such as TBMD, LD,
DFT, Morse potential function model, and modified Morse potential func-
tion model were also applied as discussed in last section.
The first technique used for simulating the behaviors of CNTs was MD
method. This method uses realistic force fields (many-body interatomic
potential functions) to determination the total energy of a system of par-
ticles. Whit the calculation of the total potential energy and force fields of
a system, the realistic calculations of the behavior and the properties of a
system of atoms and molecules can be acquired. Although the main aspect
of both MD and MC simulations methods is based on second Newton's
law, MD methods are deterministic approaches, in comparison to the MC
methods that are stochastic ones.
