# Questions tagged [computational-physics]

Questions with this tag should be about computational physics, which is the study of physical situations with the use of software (commercial or in-house). Please note that details of writing and/or debugging code is OFF-TOPIC and should be asked at either Computational Science, Code Review or Stack Overflow.

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### RGEs of the MSSM - problems with Mathematica [closed]

I'm having some troubles with the trilinear soft couplings of the MSSM RGEs. I've used the ones written in Martin's supersymmetry primer and I run them using mathematica, if I do so without taking ...
28 views

### Can we plot a FFT for a Decibel vs Seconds data?

I was plotting FFT for Decibel values corresponding to the time in which it was recorded using a DAQ for My project, The sample data looks like this, I was attempting to plot the FFT thinking that ...
59 views

### Building realistic simulation using differential equations [closed]

I am building simulation using differential equations to model the motion of a damped vertical spring-mass system. I wish to use this simulation to extract data. For example, I am trying to find the ...
104 views

### Why are numerical solutions for the Schrödinger equation necessary to plot this free waves solution?

Suppose a particle in free space given by: $$\psi(x,t) = Ae^{ik(x-\frac{\hbar k}{2m}t)} + Be^{-ik(x-\frac{\hbar k}{2m}t)}.$$ Why are numerical solutions necessary in order to plot this? Why can't ...
78 views

### How to calculate the spin correlation function for the 2d Potts model? [closed]

I basically want to make a C code for the same but I am not able to figure out how to index the array to store correlation values in terms of distance, because the distance can be non integer in the ...
91 views

### How to use numerical analysis to calculate the motion of any planet?

I have just started reading the Feynman lectures and in chapter 9, he explains how one might use numerical analysis to calculate the motion of a spring which can be extended to calculate the motion of ...
85 views

### Starting and stopping a numerical diffusion equation [closed]

I am asked to solve the following problem numerically with Python with one of Euler methods: Calculate the diffusion of particles with a diffusion constant $D=0.025$ on a surface ($24\times24$ ...
240 views

### why are qubits such a game changer in quantum computing? [duplicate]

Qubits are in a superposition which means that they can currently be both digits of 1 and 0 at the same time BUT this is my question: If Qubits have to be filtered to be used then what makes them ...
125 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 ...
1k views

### Ideas for physics-related simulations to code up as weekend (or monthly) projects [closed]

What are some good ideas for simulations that I could try to implement/code in my spare time just for educational purposes? I'm thinking that it would be a good way for me to delve into the underlying ...
42 views

### Engineering Equation Solver (EES) Entropy returning NEGATIVE numbers [closed]

I am using Engineering Equation Solver (EES). When I try to find Entropy given Temperature and Quality (liquid) at saturation pressure for carbon dioxide I keep getting a negative number. s=...
26 views

### How to color-plot a function in Polar Coordinates? [closed]

So, I have been bothering myself the past day on how to plot a Graph on Cartesian Grid (x,y), while the Variables the Function takes as Input are Polar (r,theta). This is the part of the code that ...
20 views

### Generating a flow field around a body?

How do I model (in MATLAB preferably) the following: for an arbitrary body and arbitrary flow field, generate a new flow field that goes around the body (but looks like our original flow field). ...
34 views

### Generating random change in photon frequency $\Delta \nu$ from angle-averaged isotropic redistribution function

I am implementing the Monte Carlo Simulation Code for the case of photons being scattered by electrons. The paper I'm referring (Hillier 1991, Appendix B) suggests that after each scattering, the ...
34 views

### Interpreting Slater-Koster files for DFTB

I have a question about interpreting .SKF files, I am using these parameters to model defective graphene, when I use parameter set given here: dftbBaby/C-C (I think this is from Hotbit) or the ...
38 views

### I am unable to find the RGTC package for Mathematica which is a pre-requisite for G. Compere's surface charges package, where should I look? [closed]

The link given everywhere is this but it shows Error 404. I am unable to find it elsewhere. What should I do?
127 views

### 3D sphere oblique impacts calculations

Im creating a physics simulator and im struggling to expand my collisions from 2D to 3D. In 2D the velocity only changes parallel to the line of center so I presume this is the same for 3D.I can get a ...
303 views

### Solving many-body problems with a quantum microscope

https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.118.240402 It is known that the Schrödinger equation can not be solved for many body system, but in this article cited above, the wave ...
48 views

### RGTensor (Mathematica package) Print and Plot3D functions [closed]

I plot a function for a spherically symmetric metric in RGTensor package written for Mathematica and for pressure profile I obtain a complicated plot. But then as I Print[] the corresponding pressure ...
220 views

### Solving Schrodinger equation

I have been studying quantum mechanics. I use many rectangular potential barrier to approximate real potential barrier to know transmission coefficient. I read some journal (link : http://aip....
144 views

### Lennard Jones Total system energy [closed]

i am trying to implement/extend an implementation of Lennard-Jones potential simulation regarding Xenon molecules (for curious ones, the code can be found here functions (force_naive->lj_force)). ...
46 views

345 views

### Putting high symmetry points labels to a band structure plot [closed]

So far I've got this plot using Quantum Espresso. I want to put gamma, X, L, etc labels to the k-path. Quantum Espresso's ouput states the following: ...
233 views

### How do we find the equation for the gyrating motion of a particle in a uniform magnetic field and a non-uniform Electric field? [closed]

Considering the gyrating motion is not negligible and also retaining the guiding center drift, how do we get the trajectories x(t),y(t),z(t) of the particle? In this case is the variation in the ...
152 views

### How to recognize broken candies from whole ones [closed]

Let's say I have a bag full of sugar candy. Some will be whole, some will be dent, some will be broken (in part, or half, etc). Let's say I have a device with an input box where I empty the bag, and ...
218 views

### Why does the finite difference script for solving Poisson equation not work for delta function charge? How to fix it?

I know the charge density at the plates of a capacitor, from which the applied voltage and potential profile is to be calculated. Using the finite difference method in MATLAB script I solved the ...
2k views

### Can we simulate the whole universe in computer? [closed]

Here is an idea: As human kind we discovered many laws, formulas, events, etc. in our surrounding environment.here is a way to discover the unknowns : Now if we simulate a virtual world with our ...
93 views

### Brute-forcing the theory of everything [closed]

If brute force doesn't work, you're probably just not using enough of it. That's especially true for guessing combinations of stuff, like characters in a password. Assuming some combination of ...