

Molecular Dynamics Simulation of Graphene on Rescale - gpoort
http://blog.rescale.com/running-an-md-simulation-of-graphene-on-rescale/

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Osmium
Cool demonstration of Rescale; I hadn't come across them before. It's an
interesting market, and certainly an underserved one (I say this as someone
who's idly considered running similar calculations on high-end AWS instances
and been impressed with the cost but less-so with the time it'd take to set it
all up). I imagine one of the difficult things for them is getting access to a
lot of the academic codes in widespread use at the moment, considering a lot
are under fickle and/or expensive licenses. I don't see a DFT[1] code on your
tools list at the moment; perhaps Quantum Espresso[2] (GPL-licensed) might be
a candidate if you wanted to try one.

Regarding the topic of the blog post, it's a frequent source of frustration to
me that a lot of these scientific tools are so obtuse to use. I imagine the
set of people who could understand the physics behind them and might want to
use (or just play with) them (e.g. the author of this blog post) is much
larger than the set of people who are actually capable of doing so. A good
proportion of my day is spent solving problems that are toolchain related
rather than science related and it really is immensely frustrating.

[1]
[http://en.wikipedia.org/wiki/Density_functional_theory](http://en.wikipedia.org/wiki/Density_functional_theory)

[2] [http://www.quantum-espresso.org](http://www.quantum-espresso.org)

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cogitosum
Hey Osmium, this is John from Rescale. Thanks for the code(Quantum Espresso)
suggestion. We'll make sure to add it to our software library soon!

~~~
short_circut
I actually use Quantum Espresso rather extensively in my own research. It
should work quite well with an interface like this. It has a sub-program pp.x
specifically designed to make common plots out of the programs output.

I can tell you that it tends to be a little slow compared to some other codes
such as VASP, and it does tend to take up a good deal more disk space. It has
a few other quirks but it is a great program. Also its wavefunctions can be
exported to XML files.

If you are looking anytime soon for people with computational
physics/chemistry specific knowledge I may be looking for work soon.

~~~
Osmium
> Also its wavefunctions can be exported to XML files.

Surely they'd be huge though? In any case, it's always interesting to hear
experiences about other codes. I haven't actually used Quantum Espresso
myself, but I know it's Free, so had been considering it... How would you
quantify "a little slow"?

~~~
short_circut
The xml files can be huge, but wavefunction files in general tend to be. The
main point being that it allows for direct access to the files for custom code
work.

I can quantify a little slow with a specific research experience. This isn't
the case for all uses of Quantum Espresso, etc....

When I run an HSE or PBE0 calculation on 192 atoms it takes just over 2 weeks
of computation time using quantum espresso. When my co-worker did it in vasp
using the same computing systems it took just a couple of days. I don't really
know the reason for this.

From time to time things like this creep up.

One of the quirks you should be aware of an enforce in all runs where this is
relevant is you need to set

wf_collect=.true.

if you do not then each subsequent run will require the same number of
processors in the same configuration each time the program is run.

[http://www.quantum-espresso.org/wp-
content/uploads/Doc/INPUT...](http://www.quantum-espresso.org/wp-
content/uploads/Doc/INPUT_PW.html#id3119282)

