/sci/ - Science & Math

>>9835862
To be effective; that would require a gazillion top-of-the-line super computers and or an asston of quantum computers to do.

>>9835862
Two reasons:
1. Protons and neutrons are composed of more basic types of matter, and all three are subject to phenomena more complex than the ball-and-stick model you propose, limiting such a program's usefulness.
2. Computational chemistry exists and already is a big field, but is restricted by the fact that computation becomes vastly more expensive the more particles are added, which is bad for nontrivial applications like organic chemistry and biochemistry. Quantum computers are a massive popsci meme, but one of the proposed commercial (read: useful) applications are modelling chemical reactions

>>9835862
Because to perfectly simulate an electron you would have to know both the position and momentum of it, and thr higher the accuracy of your prediction thr larger the area it could be in, so you would have to simulate an area the size of the universe to get 100% accuracy.

Basically, no. Also, no.

>>9835862
It's overkill for almost all practical problems
Shit is complicated as fuck and computing power is limited

>>9835862
We can do that since we have the exact solution for the electron wave function with a Born-Oppenheimer approximation.

We can even simulate it without the exact solution.

The problem is when you have more than one electron. We don't really understand what the potential function of a quantum mechanical field should be to begin with (there's no "point" where the charge concentrates) so you have to "guess" radial basis functions to fit it.

Finally the interactions increase combinatorially which is the worst case computational complexity (of order O(n!)) .

That is why we use models like H-F which only increase by an order O(3n) which allows the computation of state energies of large molecules using super computers in finite time.

>>9835881
>>9835884
But it's trivial to simulate balls jumping around and colliding with each other in a virtual box. Heck, I could probably do it using Java with ball objects being instances of a Ball class and with each object having values for x, y, z, (location) and s (speed). When two balls collide, a collision method could be called which would change the attributes of each ball object and make them fly apart in opposite directions in the same way they would behave according to Newtonian physics.

What makes protons, neutrons, and electrons so different and difficult to simulate?

>1. Protons and neutrons are composed of more basic types of matter,

But I thought quarks don't affect anything when it comes to chemistry.

>>9835904
>Newtonian physics.
Your trolling is too obvious.

>>9835900
This sounds like it could be the correct answer. But I only understand 1% of the words.

>>9835907
Well I'm a comp sci student but haven't taken any physics past high school level.

>>9835911
Oh, a wild CS brainlet. My mistake I thought you were a troll.

Newtonian physics doesn't apply. The particles aren't "particles" at a subatomic level.

They have a probability distribution (a wave function PDE), you compute energies by guessing a geometry, solving the PDE, integrating over the norm of the entire probability space and then finally you need to optimize the geometry to the lowest energy.

So you have 3 computational layers in the time-independent formulation.
>Optmization
>>Integration (involves a volume integral in several dimensions)
>>>PDE solutions (though this one has a few work arounds)

All of these layers are limited by the state of the art of the respective numerical methods. All of it grows O(n!) per particle without simplified models.

>>9835904
I would suggest you read up on basic physics and why it would be completely wrong to approximate particles like protons and electrons as "balls behaving according to newtonian physics"

>>9835904
i thought we abandoned the Bohr model a long time ago.

>>9835862

There's a whole field called computational chemistry, and it's a lot more complex than you're making it out to be.

>>9835904
We do do this in molecular dynamics.
You can use quantum mechanical calculations to determine the force constants for molecules
Then we can simulate many molecules with newtonian mechanics using these force constants.
This technique can be used to determine statistical properties of a system

t. guy who did computational chemistry research

>>9835862
There are cases where we do calculations like this in silico to understand things about a system. For example, if you want to look at things that happen extremely fast. Or if you want to understand how a molecule binds to an enzyme in a very short time span

>>9835862
Schrodinger equation hasn't been solved so approximations are used instead of actual real info. Not to mention computing errors compound certain fine details in reaction calculation

Further as reactions become more complex you being to run into the same constraints that actual chem has. ie: you synthesise one thing but some other random shit appears

>>9835904
you don't need to worry about the quarks and the other goings-on inside the nucleus (the nucleus is a collection of hard spheres to a very good approximation, certainly at the energy levels of chemical reactions), but you still very much need to worry about the quantum nature of the electron cloud

>>9835862
>not knowing we live in such a simulation

>>9835904
Smells like summer in here

To put it in CS terms, quantum mechanics for large systems has a lot of cyclic dependencies

The wave function of electron A depends on electrons B, C and D. They, in turn, depend on each other and A. You can brute force a solution that converges with enough iterations, but it's slow.

>>9836133
>thinking he knows anything

>>9835862
>Why hasn't anyone made a computer program that perfectly simulates a proton, neutron, and electron in a computer?
Heisenberg uncertainty principal.

>>9835862
>perfectly simulates
Perfect simulation of physics is only possible if we're in a simulation.
Otherwise uncertainty

>>9835862
Because it's basically impossible in a realistic/useful manner because it requires far more sophisticated software, models, and processors than we have. I don't think you appreciate how immensely complex reality is.