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.

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0answers
15 views

Generate unit cell from space group

I am trying to make a code to generate primitive unit cell. I have the space group and coordinate of inequivalent sites and lattice parameters. I want to generate the primitive unit cell from that. ...
0
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1answer
55 views

Failure of a simple stat mech simulation

so I did a simple simulation that I thought would yield a Boltzmann distribution, but it failed to, and I was wondering if anyone has insight into why it failed. Ok, so I had a simple discrete system ...
0
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0answers
12 views

Keplerian Orbit Estimator [migrated]

While calculating the eccentric anomaly of a satellite using the Newton-Raphson method, what initial estimate of the root for E (eccentric anomaly) should be taken for least number of iterations(best ...
2
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0answers
38 views

Epsilon Tensor in FeynCalc

A few days ago I started to use the Mathematica package FeynCalc and one thing confuses me: Assume we have a four-vector $p_\mu$ and we contract it with the epsilon tensor. FeynCalc produces ...
3
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0answers
46 views

What is the probability of quantum tunneling occurring in this CPU?

You may have noticed over the last few years that Moore's law is no longer applying to the real world. This observation states that over the history of computing hardware, the number of transistors on ...
2
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1answer
66 views

How much computer power would we need to model every physical aspect of the universe [closed]

So I know there are equations that give you the total energy in the Universe(Friedman). So about if we we to simulate every single interaction from neurons to physical forces, strong and weak, ...
2
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1answer
18 views

Why is the objective function used in Nudged Elastic Band method reasonable?

In Nudged Elastic Band (NEB) method, which is used to find reaction pathways when both initial and final states are know, an objective function is first constructed and then minimized to find reaction ...
0
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1answer
31 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 ...
3
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0answers
91 views

Comparison between Cadabra and other Symbolic Computer Algebra software [closed]

Does anyone has some experience about working with Cadabra and it's (dis)advantage in comparison to other Symbolic Computer Algebra software such as Maple and Mathematica (physics package) in the ...
1
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1answer
52 views

Rigid body collision, 3 circles in contact

I'm working on a 2d physics simulation. It's a continuous time simulation, that is, it uses swept shapes over the time-frame and geometrical/vector 'analysis' to determine most immediate time of ...
1
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0answers
24 views

How to get discretization coefficients of matrix $A$ in Finite Volume Method (FVM)? [closed]

First we have Discretization of the Transport Equation $$ \frac{\partial \rho \phi}{\partial t} + \nabla(\rho U \phi) - \nabla (\rho \Gamma_\phi \nabla \phi) = S_\phi (\phi) $$ In Finite Volume ...
3
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0answers
206 views

Numerical problem in solving the Bogoliubov de Gennes equations- methods to solve?

I am trying to solve an assignment on solving the Bogoliubov de Gennes equations self-consistently in Matlab. BdG equations in 1-Dimension are as follows:- $$\left(\begin{array}{cc} ...
1
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1answer
51 views

Getting nonphysical results when solving for the index of refraction of a slab?

I'm trying to computationally find the refractive indices (real and imaginary) for a thin slab suspended in air (so the only indices to deal with are air and my material's). I've experimentally taken ...
1
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0answers
41 views

Application of wavelets in computational electromagnetics

I am a first-year graduate student (electrical eng.); wavelets is one of the courses that I am taking presently. As part of the course, I plan to explore application of wavelets in computational ...
1
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1answer
28 views

2nd - 3rd Year Physics Labs [closed]

I'm looking to propose a new physics laboratory experiment, does anyone have any particularly fond memories of an experiment they carried out whilst at University? I'd like to include a section that ...
3
votes
1answer
114 views

confusion in discrete transform to solve kronig penney matrix equation in fourier space

I have a periodic potential $$V(x) =\sum_{K}e^{iKx}V_{K} =\sum_{n}e^{\iota2\pi nx/a}V_{n} $$ where $K =\frac{2\pi n}a$ is the reciprocal lattice vector and $a$ is the lattice constant and $n =\pm ...
1
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0answers
41 views

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 ...
1
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0answers
87 views

Numerical solution of two coupled second order differential equations of motion [closed]

Is there a numerical algorithm for solving a pair of coupled second order differential equations? This question arises from a homework problem that I have that involves two dimensional projectile ...
0
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0answers
26 views
5
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2answers
123 views

Eigenvalue problem for differential equations in QM

I have a very simple question with regard to numerical methods in physics. I want to solve the eigenvalue problem for a particle moving in an arbitrary potential. Let's take 1D to be concrete. I.e. I ...
1
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2answers
86 views

What is a good model for computing water dropping on a surface?

Before introducing my question I would like to outline the fact that I'm a coder, so I can be wrong when using some kind of terminology. What is a good model for computing the flow, the shape and all ...
2
votes
1answer
166 views

Ising model observables

Is there a formula or equation relating $\langle E\rangle$ and $\langle M\rangle$ (average spin per site) and $\langle E^2\rangle$ to temperature $T$ for the square lattice Ising model at zero ...
1
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0answers
56 views

Gerstner Wave Formula to Vertex information $(x,y,z)$

I have created a program, that draws a plane mesh, and allows to me edit or animate all the separate vertices along it. The idea behind it, is for me to be able to create a gridMesh based wave ...
1
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1answer
60 views

Motion of rigid body system in absense of work

In the absence of work on the system, is there a closed form equation for the motion of a set of constrained rigid bodies (let's say, using Revolute (ie: simple pivot) constraints)? If the bodies are ...
10
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2answers
332 views

How do you simulate chiral gauge theories on a computer?

David Tong and Lubos Motl have argued that our universe can't possibly be a digital computer simulation because chiral gauge theories can't be discretized, and the Standard Model is a chiral gauge ...
4
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1answer
129 views

How to find positions of $n$ masses in Newton mechanics?

I ran into a problem while doing research. The problem can be described as: consider the original $n$-body problem, and if we fix the position of them(unknowns), no interaction among them, they don't ...
2
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2answers
42 views

Sampling a distribution (from a galaxy model)

I am reading the following article: http://www.kof.zcu.cz/st/dis/schwarzmeier/galaxy_models.html and am currently at section 5.6 (positions of bodies in a galaxy). I am trying to redo the simulations ...
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0answers
55 views

Simulating Quantum Annealing of the Ising model on classical hardware

I would like to simulate Quantum Annealing of a 2D square lattice Ising model on a classical computer. There are many Monte Carlo based simulators on the web. However, from my very limited ...
1
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0answers
52 views

Is Bremermann's limit redundant with Landauer's limit for all practical purposes?

Trying to understand the physical limits to computation, I notice that among these we have two types of limits that constrain the minimum allowable energy for a computation. Limits that constrain ...
1
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1answer
82 views

Smoothed Particle Hydrodynamics, Chemical Reactions and Stiffness [closed]

Dear people from stackexchange physics. I have been using SPH for quite a while to simulate free boundary flow, and just recently we tried to include some kind of (simple) chemical reaction in our ...
1
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1answer
108 views

Simulation of an one dimensional driven diffusive system [closed]

I'm currently writing a simulation in python with scipy and matplotlib to reproduce an one dimensional driven diffusive system described in this paper from M.R. Evans et al. The system consists of ...
1
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0answers
40 views

Find out ground sates for large 2D classical spin model

Reaching the ground state of a large 2D classical spin model (e.g. classical Heisenberg model) might be a relatively difficult task while using conventional "flip/reject" Monte Carlo method. The ...
2
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3answers
141 views

Do algorithms have an intrinsic time direction?

This article says There is no intrinsic time direction in Newton's mechanics nor in the differential equations of the new physics. My question is, do other types of mathematics, say a cellular ...
4
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1answer
75 views

Can computers accurately model all of the details (to the subatomic level) of macro objects in collisions?

Frequently when trying to solve cosmology questions physicists turn to computer simulations of the universe (albeit massively simplified) in order to verify or disprove their hypotheses. This got me ...
10
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3answers
2k views

How are physics and computer science getting united?

How is theoretical computer science getting united with physics? Phenomena like Quantum Computing uses Quantum Mechanics to be able to compute things, how are computers helping not just to model our ...
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0answers
26 views

Capacitance of an arbitrary electrode configuration

I have to find the capacitance of a circuit element in three dimensions. I have the potential and charge in this cross sectional slice calculated using numerical methods. Does this value of ...
7
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2answers
301 views

Diifference between real time propagation and imaginary time propagation?

Suppose I want to solve Nonlinear Schrodinger equation using imaginary time propagation to get the ground state solution. I choose $t = - i t$, and then solve the equation using split step Crank ...
0
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1answer
230 views

Acceptance probability 2D Ising Model

Disclaimer: I just found a possible solution - eventhough i don't really understand, whats wrong with my prior approach. Edit: I just tried to calculate it from scratch and found the following: $E ...
-3
votes
1answer
103 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 ...
7
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4answers
492 views

Church-Turing hypothesis as a fundamental law of physics

The Church-Turing hypothesis says one can not build a computing device which has more computing power (in terms of computability) than the abstract model of Turing machine. So, there is something in ...
1
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2answers
70 views

Discrete approximation of charge density

Given the electric potential $\Phi(r)$ and the Poisson's equation: $$ \nabla^2 \Phi(r) = - 4\pi \rho(r)$$ Consider the 2-dimensional case and let's say that I want to discretize this using a square ...
3
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2answers
490 views

Implementing simple atom model using density functional theory (DFT)

I am trying to write computer code which will find the energy and density function for an atom with $Z$ protons and $N$ electrons. I am working in 1D for simplicity and would like to make the overall ...
1
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1answer
49 views

what is two species Bose Hubbard Model? what chage it takes on Fock basis representation?

The Hamiltonian will look like \begin{equation} \ H= -t^a\sum_{<i,j>}^{}(a_i^\dagger a_i + h.c.)-t^b\sum_{<i,j>}^{}(b_i^\dagger b_i + ...
0
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0answers
31 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 ...
0
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1answer
99 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 ...
0
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0answers
35 views

Are there any programs or codes widely used for computing spherical multipole expansion, especially for CMB?

I have data of coordinates and values of a part of sky, and I'm supposed to calculate multipole expansion, change some components between some $\ell$s, and finally calculate back to values. The ...
0
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2answers
95 views

Grand canonical ensemble with interaction, simulation doubts

First of all, this is a follow-up of my first question. The idea is the same, every state would consist of some particles in a line (with an energy associated) and the particles can not be nearer than ...
14
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5answers
571 views

Home-made lattice calculation?

The topic of Lattice QCD or Lattice gauge theory or even Lattice field theory is quite old now. And the main reason for the interest in the topic is the ability to calculate nonperturbative stuff on a ...
0
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1answer
134 views

Reference-request: Computational science and physics [closed]

I'm interested in the following question: Is Nature computable at it's most fundamental level? Can anyone suggest any works (books, papers / articles, reviews) related to the above question? ...
2
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0answers
167 views

Detailed procedures of numerical calculations in lattice models [closed]

I am looking for a reference to show me a detailed procedure of numerical calculation of a physical quantity of a lattice. I have knowledge of the physics part and I am able to find it. My problem ...