# Tagged Questions

Subdiscipline of theoretical physics which consists in the study of physics problems using numerical algorithms. PLEASE NOTE that questions about computational methods and/or programming are OFF-TOPIC on Physics.SE.

15 views

### Numerically evaluating momentum sums

For many-body systems, calculations often involve momentum sums, which are ultimately evaluated numerically for a finite system size $N$. The larger $N$ is, the more accurate the results. Is there ...
19 views

### Numerical computation of electric multipoles

I'm trying to do a plot of the first multipole terms in Mathematica. My plot isn't what I expected, so maybe my problem is in the mathematics. Following the Griffiths' book on Electrodynamics, the ...
13 views

### Smoothed particle Hydrodynamics (SPH), changing length of smoothing kernel makes sim unstable

I am trying to simulate water for a video game. Now I need to make the smoothing length .1 of it's original value, however the simulation explodes. What constants and by how much should I change ...
75 views

### What is the output of a simulation of quantum particles? [closed]

When physicists simulate a quantum system, what is the output of such computation? Is it the probability wave function of the system? What if the system consists of enough particles to be considered ...
821 views

### Comparison of different ab-initio codes

One may find on the web a lot of different computational packages to perform "ab-initio" calculations of electron structure of the solids. Usually, the documentation is not quite transparent about the ...
233 views

### The use of Artificial Intelligence in physics resarch [on hold]

I have been reading about a machine that observed a double pendulum and created equations that both described its motion and associated conservation laws. The authors claims: We have developed a ...
149 views

### Deriving the change in the Helmholtz free energy in the context of the free energy perturbation method

I am reading Free Energy Calculations: Theory and Applications in Chemistry and Biology by Chipot and Pohorille. At the beginning of the text (page 19, for example), the authors define the Helmholtz ...
162 views

### Modelling multiple heat sources?

I am working on a project to model heat transfer in a data center. I have basic models for a one dimensional heat transfer using conduction and convection. Such as, taking a server and modelling the ...
58 views

### Experiments to resolve dillema between continuity and discrete

Which experiments/experimental methods are suggested to resolve an alternative about the structure of our universe space and time - is it continuous or is it discrete in a very small scale, especially ...
5k views

### Is there any aspect of an explosion resulting from a nuclear weapon test that cannot be simulated using super computers?

This Washington Post news article states that with the advent of computer simulation of nuclear tests, live tests are no longer needed. Generally speaking there are 3 aspects of an explosion ...
59 views

### Numerical relativity in causally pathological spacetimes

To perform numerical relativity simulations one almost universally adopts the so called "3+1" approach: spacetime is divided up into spacelike slices, each representing a "moment in time". After some ...
16 views

### canonical ensemble density matrix numerical integration of the von Neumann equation

I am working with a numerically calculated Eigensystem of a given non-linear Hamiltonian. As a test I integrated SchrÃ¶dinger equation for each eigenstate in time with Dormand Prince 54 and also Runge ...
29 views

### Single fluid simulation algorithm

Every fluid simulation I've seen implicitly involves a fluid that isn't mentioned, usually air. This is clear because the simulation usually has an ambient temperature, and always an ambient velocity. ...
26 views

### Why will a Fourier transform of a pickup placed at the middle of a string only result in odd harmonics?

My physics teacher explained a lot of information about strings but he never went in depth with my question. What happens to the even harmonics and why are the odd ones the only ones picked up?
26 views

### recovering numerical wave function using path integral after Wick rotation

I have written two different path-integral codes, PATHINT and PATHTREE, to numerically solve some classical-physics problems in nonlinear systems, finance and neuroscience. They work just fine. My ...
27 views

324 views

### Arrhenius Fit: Linear or exponential form?

I have a seemingly easy question about performing an Arrhenius fit to the equation $$y = A \times \exp \left( -\frac{E_A}{RT} \right)$$ I can either fit this in the exponential form using a ...
I am trying to write a code to calculate the potential and forces, for the same using ewald summation.For this purpose, the formula for potential and force I have used is :  U = U^{(r)} + U^{(k)} ...