Questions tagged [computational-physics]
Computational physics is the study and implementation of numerical algorithms to solve problems in physics for which a quantitative theory already exists.
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questions with no upvoted or accepted answers
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DIIS method to accelerate SCF convergence for stretched geometries
I am implementing from scratch an Hartree-Fock calculation in the STO-3G basis set to perform Born-Oppenheimer molecular dynamics. I have a Restricted Hartree-Fock procedure that can reproduce very ...
user18279
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Is a complete bacteria simulation with an exascale supercomputer possible?
Will it be possible to simulate a complete (at least simple) bacteria atom by atom on an exascale supercomputer? or is it possible already today with the largest systems?
Here, I've read that ...
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Computation of Troullier-Martins pseudowavefunctions
The computation of Troullier-Martins pseudo-wavefunctions has been
described in [1].
The pseudo-wavefunction $R^{\textrm{PP}}_l$ is defined by
$$
R^{\textrm{PP}}_l(r) =
\left\{
\begin{array}{ll}
R^{\...
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Non-reflecting boundary conditions for compressible Navier-Stokes equations
I have some questions about the implementation of non-reflecting OUTFLOW boundary condition for Navier Stokes equations.
Following
Poinsot, Lele "Boundary Conditions for Direct Simulations of ...
- 139
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votes
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Phase dislocations and numerical accuracy
I am solving the nonlinear Schrodinger equation (NLSE),
$$A_t+iA_{xx}+i|A|^2A=0$$
where $A$ is a complex valued function, which can be written as $A=ae^{i\theta}$ for $a,\theta$ real. Now, for ...
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How to take the Fourier transform of a Fibonacci chain in a Python script?
This may be an easy question to answer but I am really stuck.
In several topics (especially that of quasicrystals) the Fibonacci chain's Fourier transform and diffraction pattern is mentioned. Despite ...
- 1,068
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votes
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Looking for non-trivial examples of solutions to 3D wave equations?
We have developed a (new) numerical scheme to solve the classical wave equation in 3 dimensions and we aim to publish the results.
We can read in the aim and scope of the journal of computational and ...
- 151
3
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Numerical Soultion to Background equations of cosmology
I am trying to solve the background equations of cosmology numerically using Runge-Kutta Dormand Prince method with simplified assumption $8\pi G=1$ and $c=1$. The equations are
$$\ddot a = - \frac{1}{...
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Python routine to calculate shape resonances of H2
I am currently doing a project in which my aim is to write a program that can be used to calculate single and multi-channel shape resonances. So I'm looking at bound states and quasi-bound states.
...
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Choosing good modelling method for solving Boltzmann equation
I'm writing a solver for Boltzmann Equations (BE) including a force term in rarefied plasma, for my PhD. The aim is to see if an instability occurs inside an electric streamer (theoretically it should,...
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Should I expect computational gains using a second-order splitting method here?
I am trying to solve a three-dimensional baroclinic transport problem. The hydrodynamic (three-dimensional shallow water) equations are:
\begin{align}
\nabla \cdot \vec{v} = 0, \tag{1} \\
\frac{\...
- 389
3
votes
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Crank-Nicolson integrator: oscillations with complex matrix
I'm working on a Real-Time TDDFT implementation and I am currently comparing different propagation schemes for the propagation of the Kohn-Sham wave function,
$$
\phi(t+\Delta t) = \hat{\mathcal{U}}\...
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votes
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How can I evaluate the accuracy of my n-body simulation?
I am making an n-body simulation in python. There are many different methods to numerically solve the system of differential equations governing the gravitational interactions between the $n$ ...
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Cavity Flow CFD Boundary conditions and strange waves
So I have a PDE that I use to describe how material flows through a volume(2D or 3D).
$$\frac{\partial C}{\partial t} + \vec{u} \cdot \nabla C = (D' + D )\nabla^2C$$
Now using finite differences I get ...
3
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Numerical error in implementation of iterative algorithm
I am trying to implement (in Python for now) low thrust orbit propagation for spacecraft using universal variables. For a given central body with the gravitational parameter $\mu$ and an orbit with ...
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