Is there any research going on the simulation of atoms.

like collisions of two or more atoms of any kind .(not in reality but
on computers)

are there any softwares available for such tasks ?

On Jun 29, 9:35M-BM- pm, spike wrote:
Is there any research going on the simulation of atoms.

like collisions of two or more atoms of any kind .(not in reality but
on computers)

are there any softwares available for such tasks --

i have heard the commercial package gaussian does some atomic
and molecular dynamics using semi-classical methods. not a full
quantum mechanical scattering treatment, although the molecular
structure calculation in gaussian are fully quantum mechanical.

spike wrote:
Is there any research going on the simulation of atoms.

like collisions of two or more atoms of any kind .(not in reality but
on computers)

are there any softwares available for such tasks ?

There are some groups concerned with reactive scattering of three to five
atom systems. These systems can be investigated with full quantitative
quantum mechanical treatments of all relevant physical effects of both the
electronic structure and the reactive scattering itself.

Some pointers on recent work in this direction:

Hu,Schaty, Theories of reactive scattering, J. Chem. Phys. 125, 132301
(2006); DOI:10.1063/1.2213961

Che et al, Breakdown of the Born-Oppenheimer Approximation in the F +
o-D2 - DF + D Reaction, Science 317, 1061 (2007),
DOI:10.1126/science.1144984

De Fazio et al - Exact state-to-state quantum dynamics of the
F+HD--HF(v[prime]=2)+D reaction on model potential energy surfaces, J.
Chem. Phys. 129, 064303 (2008); DOI:10.1063/1.2964103

Wu, Werner, Manthe - First-Principles Theory for the H + CH4 - H2 + CH3
Reaction, Science 306, 2227 (2004), DOI:10.1126/science.1104085

etc. You can find much more in this direction by following the citations of
the potential energy surface articles in Google Scholars or other cross
references in the articles.

Typically several programs need to be applied, and these kinds of
simulations are not routine tasks. You'd need a program which is able to do
good Multireference CI treatments for electronic potential energy surfaces
(e.g., MOLPRO), something to calculate and parameterize the PES based on
that, and another one to do the actual scattering simulations.
--
- C. Gerald Knizia/cgk | #28673212 | this mail was made with intention.

Thanks Vivishek and Gerald

Well my query was limited to two-to-three body systems(atoms/
molecules), Now i would like to point out the specific use i am
looking for.

Suppose these simulations are done on a large scale(real big),like a
tree(whoops !), a fan ?
I am still talking small, how about a lake(lots of water !!!).
EARTH(too much complicated) ?
UNIVERSE ? (or a random universe formed by collisions of these atoms)

or just millions of atoms interacting in a closed space(study for gas
equations! or The BIG BANG !).

well i am a high school student so i was just curious, you can already
see i am unaware of a lots of physics and limitations of the current
technology.

but still i would like to see the progress that has been made in this
field.

On Jul 4, 12:47*pm, spike wrote:
Thanks *Vivishek *and Gerald

Well my query was limited to two-to-three body systems(atoms/
molecules), Now i would like to point out the specific use i am
looking for.

Suppose these simulations are done on a large scale(real big),like a
tree(whoops !), a fan ?
I am still talking small, how about a lake(lots of water !!!).
EARTH(too much complicated) ?
UNIVERSE ? (or a random universe formed by collisions of these atoms)

or just millions of atoms interacting in a closed space(study for gas
equations! or * The BIG BANG !).

ha ha.. once you see how much time and computational effort it takes
to solve even the simplest of dynamical simulations, you wouldnt be
thinking on such grand scales.
for example, a simulation of a simple potential energy surface based
two-atom collision takes about 8 hours of computational time
on a 6 core Sun UltraSPARC cluster!

now for an interacting fluid system (even multiphase flows), the
preferred method, taking into account computational cost,
is a cellular automata based simulation. Such methods have been used
with great success in various complex situations where a direct
solution of the dynamical equations (navier-stokes in this case)
poses a huge computational challenge.

but i have no idea if such methods can be extended to systems like
a universe whose dynamical equations are still not completely well
known.