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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39 views

Why breakdown voltage decreases with increasing FWHM of an asperity?

I am running a simulation for a dielectric breakdown. I am getting breakdown voltage decreases with FWHM, which does not make sense as field enhancement is higher for a small width. Simulations solve ...
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1answer
71 views

2D room with electron-point-charges (stability)

Is there a fast way to find out stable #"point charges" & constellation for this kind of Simulation. The 2D repeating itselve in each direction till infinity, so i've a kind of symetrie here. Red ...
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523 views

Boundary conditions of stream function

I have to do an problem about solving numerically the flow that goes under an airfoil. The airfoil has a flap deployed downwards and I need to solve the mesh that it's under the airfoil. I have drawn ...
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138 views

Examples of application of detour matrices in physics?

Are there any good examples of application of detour matrices in physics?
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1answer
91 views

Learning material on optical computing

I'm looking for guidance to choose material for a self-study of photonics, biased towards optical computing recent advances. My background is of undergraduate level electrodynamics, quantum mechanics,...
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1answer
273 views

How to Extend Relaxation Methods for 2D Laplace Equation given in Jackson E&M to 3D?

In Jackson (3 ed) chapter 1.13 an outline is given for using relaxation to solve laplace equation in 2D. The general procedure in 3D involves minimizing the quantity $$I[\Psi]=\frac{1}{2}\int_V \...
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562 views

Numerical solution of the BCS gap equation, with Coulomb potential

I'm interested in the excitons condensation, which is described by an equation which is very similar to the standard BCS gap equation. I will be referring to this article: http://arxiv.org/abs/cond-...
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62 views

Should particles in Smoothed Particle Hydrodynamics (SPH) always move during a simulation?

Or can they just be used as an interpolation points and use some other "transported property" which are just evolved and propagated from boundary conditions like for eg. heat conduction through a ...
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1answer
175 views

Plane Wave expansion method

I really don't know if this is the right forum to ask the question...but please help me if you can!! I was going through the Plane Wave Expansion Method Derivation...But to be honest I could not find ...
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89 views

Can peridynamics give accurate quantitative results?

I'm applying for a position that is interested in studying crack growth using peridynamics. I have experience with MD on polymeric systems, but I had never knew of this method before. It seems very ...
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135 views

numerical diagonalisation comparison of complex Hermition matrix and real matrix

we are doing K space calculation(transnational invariant basis) of Hamiltonian, and trying to compare with exact method for same nos of sites and particles, we are getting big difference in ground ...
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1answer
53 views

Physics Graphic Simulations

I am interested in modeling physics using graphics simulations. I took a python course with CS majors and one of the assignments was to simulate a planet orbiting a star. That being said, I was ...
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1answer
108 views

Simple iterative method to obtain any ground state given Hamiltonian operator

So, I'm considering the operator $\frac{h_0}{\bf H}$ with $\bf H$ any hamiltonian operator and $h_0$ a small non-zero positive constant with dimensions of energy and assumed to bound by below all ...
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1answer
158 views

What exactly is closed orbit theory and what assumptions go into it?

I am just beginning a research project on the study of closed orbits, specifically as related to hydrogen, and I wanted a little bit more information on what exactly makes something a "closed orbit". ...
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2answers
57 views

Can quantitative model explain away our world? [duplicate]

So, for the sake of argument, let us assume that we have sufficient computational power and brightest scientists. Can we explain/predict every aspect and event of our universe with quantitative model? ...
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2answers
139 views

What is the physical meaning of the integral of momentum with respect to time?

i am asking myself what the physical meaning of $$\int \mathbf{p}(t)dt$$ would be. I want to provide a bit more context why i am asking myself that: I use a particle based simulation system, where ...
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147 views

Hydrogen in a box

I would like to approximate the 1S wave function of a system constrained to a box $\{(x,y,z)|x\in[0,a],y\in[0,b],z\in[0,c]\}$, subject to the potential of the hydrogen atom. I have proposed the ...
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2answers
103 views

Can we create new physics through moderately brute force computing? [closed]

So my argument for this is that the expansion of knowledge in any field of physics depends on what is previously known, and what we physicists express or knowledge as equations. So here's what I ...
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1answer
96 views

Numerical approximation of the wavefunction in a delta-potential [closed]

I am trying to approximate the wavefunction of a particle in a delta potential $U(x) = -U_0 \delta(x)$ with $V_0 \gt 0$. I am using the following formula to calculate the wavefunction: $\psi(x+\Delta ...
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1answer
112 views

What is the pressure difference between capillaries and the outside air?

Why exactly do we bleed? There is a pressure gradient that causes the blood to flow from the capillaries to the outside of the skin. What is this pressure difference? The pressure inside the ...
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1answer
55 views

Time dilation in the Reissner-Nordström metric [closed]

According to Wikipedia, the formula for gravitational time dilation in the vicinity of a charged mass is: $$\varsigma = \sqrt{|g^{t t}|} = \sqrt{\frac{r^2}{Q^2+(r-2 M) r}}$$ However, if I plug in $M=...
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1answer
73 views

Modelling lunar motion in Python [closed]

I'm trying to solve the equations of motion of the Moon in the Moon-Sun-Earth system (equations 1139-1141 here:http://farside.ph.utexas.edu/teaching/336k/Newtonhtml/node130.html) My initial ...
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1answer
129 views

Determine velocity of balloon from known Buoyancy, mass and surface [closed]

I need to know how to get velocity of weather balloon, if I know it's buoyancy force, mass and surface(diameter). I am using now $$v = 0.5t\left(\frac{F_\text{all}}{m}\right),$$ [$m$ = mass, $v$ = ...
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1answer
716 views

Mercury's perihelion precession [closed]

i want to plot the precession of mercury's perihelion in MatLaB .(like the image below).Help me out here ,guys. https://en.wikipedia.org/wiki/Apsidal_precession#/media/File:Perihelion_precession.svg ...
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1answer
459 views

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 ...
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1answer
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 ...
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1answer
103 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 ...
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1answer
77 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 ...
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1answer
88 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 ...
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1answer
83 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 ($24\times24$ ...
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1answer
234 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 ...
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2answers
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 ...
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1answer
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 ...
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0answers
15 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 ...
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1answer
122 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 ...
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1answer
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 ...
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1answer
47 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 ...
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1answer
218 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....
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1answer
134 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)). ...
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1answer
73 views

Resource recommendation for machine learning

I am planing to change my field (in PhD) and learn Machine Learning to differentiate different phases of strongly correlated matter. I learned Monte Carlo method in my MS and have intermediate level ...
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1answer
46 views

Non-linear optics - solve differential equations coupled with the finite difference method [closed]

I have these three differential equations in which I need to solve numerically: $$ \frac{dn_0}{dt}= -n_0(t)W_{01}(t) + n_1(t)K_{10} $$ $$ \frac{dn_1}{dt}= -n_1(t)W_{12}(t) - n_1(t)K_{10} + n_2(t)K_{...
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1answer
80 views

Help with 2nd Order Coupled ODEs [closed]

I am trying to solve a 2nd Order Coupled ODE for A "Looping Pendulum" numerically with MATLAB. Can anyone please recommend how? (which ODE solver to use) Thanks!
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1answer
26 views

How to plot a vector field? [closed]

I am reading articles of vector fields, such as magnetic field and sound field. I am very curious about how the vector fields are drawn, such as the pictures shown below. Any reference to this ...
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2answers
128 views

Standards for scientific metadata in common-use image formats? [closed]

I have a bunch of JPEG, JPEG2000 GIF and PNG files that in theory could be used for some types of science analysis if there were temporal and spatial information in them. Years ago, I had looked into ...
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3answers
404 views

Is Physics Computable? [closed]

Is it possible for a Turing machine to simulate physics accurately?   For the problem of reals, I was thinking of the following: For each real, $2^1, 2^2, ...., 2^n, ...$ memory cells store the ...
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1answer
98 views

Software for calculating the trajectory of a body in a coordinate system

I'm looking for a program, which would simulate the path of motion of a body in a coordinate system, given the force acting upon the body. I'd type in the initial conditions such as the velocity, $(x,...
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1answer
181 views

I am looking for 'Programming+Electronics+ Physics' field [closed]

I wish to pursue a career that somehow involves programming, electronics, and physics. What are such careers? Also, I have heard of some 1 year post-graduate diplomas/courses for specialization in ...
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2answers
74 views

Data transmission in optical fibers

Im reading though my Network Architecture lecture notes and it states optical fibers need a repeater every >10km. Repeaters are used to amplify digital signals but the notes do not explain or state ...