Hi Vitaly,
Do you mean that if you start with two different starting points, you
end up with two different tensors? For the different rounds of
iterations do you mean from the dauvergne_protocol.py script? Are the
chi-squared values the same in both? There might also have been a fix
for the diffusion tensor representation in more recent relax versions.
Are you using the newest 1.3.13 version? Running 'relax -i' will
give all the version info. There are symmetries in the diffusion
tensor space, so two {theta, phi} pairs with different values can
represent exactly the same tensor. Though the different tensors are
very strange, especially considering that the tm and Dratio values are
essentially identical! Are you using Modelfree4 as a back end
optimisation engine?
Regards,
Edward
On 23 January 2012 18:03, V.V. <vvostri@xxxxxxxxx> wrote:
Dear Edward,
I have encountered strange behavior with the initialization of the
diffusion tensor. I ran the first round of iterations, ending up with
the following oblate tensor:
===============================
Alternate parameters {tm, Dratio, theta, phi}.
tm (s): 9.486979075650368e-09
Dratio: 0.6141733435119592
theta (rad): 3.64621046835412
phi (rad): 1.9625997908540063
===============================
For the next round of model-free optimization, I have specified these
parameters manually:
===============================
diffusion_tensor.init((9.486979075650368e-09, 0.6141733435119592,
3.64621046835412, 1.9625997908540063), param_types=2,
spheroid_type='oblate', fixed=True)
===============================
Yet in this round the diffusion tensor was showing up with different
Theta and Phi angles:
===============================
Alternate parameters {tm, Dratio, theta, phi}.
tm (s): 9.486979075650368e-09
Dratio: 0.6141733435119593
theta (rad): 0.0636383778934639
phi (rad): 0.0342538282493545
===============================
I have generated pdbs of both tensors and they are not identical. Do
you have any suggestions what is causing this?
Thank you,
Vitaly
Re: Tensor Euler angles