# 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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### Leapfrog method in Particle-in-cell

Recently, I wanted to write a 3D electromagnetic Particle-in-cell code with C++. I know that I should use leapfrog method, for example, when I calculate the position and velocity of particles，I should ...
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### How does the Lennard Jones Potential changes for interaction between particles of different sizes?

I am interested in incorporating a Lennard-Jones potential in a simulation. When the interaction only involves the same type of particle, with same characteristics, we can use reduced units, scaling ...
766 views

### How Much Computing Power would be Required to Fully Simulate a Cubic Meter? [closed]

Imagine you want to simulate a cubic meter down to the particle. By following the Standard Model and other basic physical equations, how much computing power would be required to do this, in say, a ...
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### Big Data Handling at the LHC

My understanding is that much of the data that is is collected at the Large Hadron Collider is similar to that in the image below, and that a vast amount of the data contains little of specific and ...
309 views

### Numerical Tools and Related Resoures for Bohmian Mechanics

I am trying to do some simulations using the de Broglie - Bohm formalism and am wondering if there are computational tools that already exist in this area. I generally use Python, but will consider ...
312 views

### How to propagate $E_x (x,t) = \exp(-t^2/\tau^2-i\omega_0 t) \exp(-x^2/w_0^2)$ in finite difference time domain (FDTD) analysis

Finite difference time domain (FDTD) allows to solve differential equations for time evolution. For example, we can analyze ultra-short pulses in free space by solving the Maxwell's equations. The ...
128 views

### Possibility of simulating quantum physics and relativity [closed]

I must be clear; this is not a 'specific' question, but rather a hypothetical one. As of now, computer physics simulations are becoming more and more advanced, and I am programming one now. I was ...
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### Montecarlo simulation, Metropolis algorithm

I'm trying to study the thermodynamics of an N particles system in a fixed volume. In particular, I'm using Metropolis algorithm for simulating the dynamics of such system. My interest is to calculate ...
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### Can someone please explain the second term of the expression for mass flow across the fluid element?

I've recently started studying from the text "An Introduction to Computational Fluid Dynamics" by Versteeg and Malalasekera. I'm currently on the topic of derivation of the fundamental governing ...
364 views

### Numerically solving a particle in a box problem

A particle in box problem can be simplified to second order differential equation as: $$-\frac{d^2}{dx^2}\psi(x)=E\psi(x)$$ with the boundary conditions: $$\psi(1)=\psi(0)=0$$ The goal is to ...
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### Sampling Maxwell-Jüttner distribution for non-unity mass and speed of light

I am trying to sample Maxwell-Jüttner distribution using the Sobol method as described in Zenitani Loading relativistic Maxwell distributions in particle simulations (2015). Equation (2) in the paper ...
36 views

### Optical Logic Gates using Polarisers [closed]

I am trying to build an optical logic circuit using the horizontal or vertical orientations of light as the two binary states and laser as the source. Before I ask you my question I wanted to first ...
108 views

### How can I use Runge-Kutta4 to solve this orbit in polar coordinates?

I want to simulate a simple orbit of a planet moving around a star which is fixed in position. I have formulated the ODEs for this problem using Lagrangian Mechanics and have found the equations of ...
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### When intersections of trajectories in Poincare sections are possible?

If we get intersections of some "trajectories" in non-standard 2D Poincare sections, that have been obtained from numerical integration of Hamilton equations for autonomous system in 2D coordinate ...
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### Solving analytic solution to 1st, 2nd and 3rd order

I'm currently reading a review paper on quintessence (https://arxiv.org/abs/1304.1961) and in §3.1 he plots the evolution of the equation of state parameter $w$ with the scale factor $a$. He produces ...
319 views

### How to simulate a phase transition in Molecular Dynamics?

I am trying to simulate the phase transition for gold and silicon separately using LAMMPS. I got the melting point for gold right using the below code. ...
179 views

### “Non-smooth” flow of liquid poured from a milk carton

With milk poured from a newly opened carton, I have observed over the years that the flow of the liquid starts off flowing smoothly and continuously but after some time t becomes "sporadic" in such a ...
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### What is a stoquastic Hamiltonian?

Recently, I've often read about the term 'stoquastic Hamiltonian'. But I couldn't find a precise definition anywhere. I found that the Ising-Hamiltonian is a stoquastic Hamiltonian, but that does not ...
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### Are there some necessary and sufficient conditions that a system can be modeled using Monte Carlo Methods?

Is there a certain set of conditions a system need to follow such that it can be effectively modeled using any "general" Monte Carlo method, maybe to find some average value of a thermodynamic ...