Recent content by alyflex

What I'm actually doing: I'm doing imaginary time propagation in density functional theory. So after each iteration I have to othogonalize my orbitals, this is done by subspace othogonalization, in which I create the overlap matrix M_ij, to get the new orbitals I then solve the coresponding...

Hi guys I have a problem that I need some help with, I am looking for a direct eigenvalue solver algorithm. The problem is that all the eigenvalue solvers I can find seems to reorder the final matrix after the size of the eigenvalues. The matrix it shall calculate is very small (5-10)...

I'm not allocating it in the main program, but I have tried it anyways, with no succes.

Hi, I have a rather large program written in fortran 77/90. In one of the subroutines a lot of local dynamic arrays are declared. In order to make this program able to calculate more stuff, I need to bring these dynamic arrays back into the main program. I have tried to define the...

Well I just went through the calculation myself and as far as I can see everything you wrote was spot on, so thank you very much. Btw I had no idea that the linsolve function in MATLAB solved a system of linear equations using least squares, I only thought it could find consistent solutions.

It would seem that way, but it can be shown that any constant potential can be absorbed by the phase if I remember correctly. Just try to redefine the energy yourself and see if anything changes.

Thank you very much for the illuminating answer trambolin. I'm going to work it through in the weekend using your method. I'll post a longer and more conclusive reply once I have tried the method. But to all of you, thank you very much for an enlightening discussion on a subject, which...

This was what I suspected, but thanks for making it clear. Now I just need a method to compute it for non-invertible matrices The more I look at this the more afraid I am, that a numerical solution might be the best way. I was really hoping for a clear and illuminating analytical method. The...

I have stumbled upon a problem which I have so far been unable to solve. I we consider a general set of linear equations: Ax=b, I know the the system is inconsistent which makes least square method the logical choice. So the mission is to minimize ||Ax-b|| And the usual way I do...