mirror of
https://github.com/QuantumPackage/qp2.git
synced 2024-08-31 08:13:43 +02:00
123 lines
3.8 KiB
Org Mode
123 lines
3.8 KiB
Org Mode
|
* Agreement with the model: Rho
|
||
|
|
||
|
*Compute the ratio : rho = (prev_energy - energy) / (prev_energy - e_model)*
|
||
|
|
||
|
Rho represents the agreement between the model (the predicted energy
|
||
|
by the Taylor expansion truncated at the 2nd order) and the real
|
||
|
energy :
|
||
|
|
||
|
\begin{equation}
|
||
|
\rho^{k+1} = \frac{E^{k} - E^{k+1}}{E^{k} - m^{k+1}}
|
||
|
\end{equation}
|
||
|
With :
|
||
|
$E^{k}$ the energy at the previous iteration
|
||
|
$E^{k+1}$ the energy at the actual iteration
|
||
|
$m^{k+1}$ the predicted energy for the actual iteration
|
||
|
(cf. trust_e_model)
|
||
|
|
||
|
If $\rho \approx 1$, the agreement is good, contrary to $\rho \approx 0$.
|
||
|
If $\rho \leq 0$ the previous energy is lower than the actual
|
||
|
energy. We have to cancel the last step and use a smaller trust
|
||
|
region.
|
||
|
Here we cancel the last step if $\rho < 0.1$, because even if
|
||
|
the energy decreases, the agreement is bad, i.e., the Taylor expansion
|
||
|
truncated at the second order doesn't represent correctly the energy
|
||
|
landscape. So it's better to cancel the step and restart with a
|
||
|
smaller trust region.
|
||
|
|
||
|
Provided in qp_edit:
|
||
|
| thresh_rho |
|
||
|
|
||
|
Input:
|
||
|
| prev_energy | double precision | previous energy (energy before the rotation) |
|
||
|
| e_model | double precision | predicted energy after the rotation |
|
||
|
|
||
|
Output:
|
||
|
| rho | double precision | the agreement between the model (predicted) and the real energy |
|
||
|
| prev_energy | double precision | if rho >= 0.1 the actual energy becomes the previous energy |
|
||
|
| | | else the previous energy doesn't change |
|
||
|
|
||
|
Internal:
|
||
|
| energy | double precision | energy (real) after the rotation |
|
||
|
| i | integer | index |
|
||
|
| t* | double precision | time |
|
||
|
|
||
|
#+BEGIN_SRC f90 :comments org :tangle trust_region_rho.irp.f
|
||
|
subroutine trust_region_rho(prev_energy, energy,e_model,rho)
|
||
|
|
||
|
include 'pi.h'
|
||
|
|
||
|
!BEGIN_DOC
|
||
|
! Compute rho, the agreement between the predicted criterion/energy and the real one
|
||
|
!END_DOC
|
||
|
|
||
|
implicit none
|
||
|
|
||
|
! Variables
|
||
|
|
||
|
! In
|
||
|
double precision, intent(inout) :: prev_energy
|
||
|
double precision, intent(in) :: e_model, energy
|
||
|
|
||
|
! Out
|
||
|
double precision, intent(out) :: rho
|
||
|
|
||
|
! Internal
|
||
|
double precision :: t1, t2, t3
|
||
|
integer :: i
|
||
|
|
||
|
print*,''
|
||
|
print*,'---Rho_model---'
|
||
|
|
||
|
!call wall_time(t1)
|
||
|
#+END_SRC
|
||
|
|
||
|
** Rho
|
||
|
\begin{equation}
|
||
|
\rho^{k+1} = \frac{E^{k} - E^{k+1}}{E^{k} - m^{k+1}}
|
||
|
\end{equation}
|
||
|
|
||
|
In function of $\rho$ th step can be accepted or cancelled.
|
||
|
|
||
|
If we cancel the last step (k+1), the previous energy (k) doesn't
|
||
|
change!
|
||
|
If the step (k+1) is accepted, then the "previous energy" becomes E(k+1)
|
||
|
|
||
|
#+BEGIN_SRC f90 :comments org :tangle trust_region_rho.irp.f
|
||
|
! Already done in an other subroutine
|
||
|
!if (ABS(prev_energy - e_model) < 1d-12) then
|
||
|
! print*,'WARNING: prev_energy - e_model < 1d-12'
|
||
|
! print*,'=> rho will tend toward infinity'
|
||
|
! print*,'Check you convergence criterion !'
|
||
|
!endif
|
||
|
|
||
|
rho = (prev_energy - energy) / (prev_energy - e_model)
|
||
|
|
||
|
!print*, 'previous energy, prev_energy:', prev_energy
|
||
|
!print*, 'predicted energy, e_model:', e_model
|
||
|
!print*, 'real energy, energy:', energy
|
||
|
!print*, 'prev_energy - energy:', prev_energy - energy
|
||
|
!print*, 'prev_energy - e_model:', prev_energy - e_model
|
||
|
print*, 'Rho:', rho
|
||
|
!print*, 'Threshold for rho:', thresh_rho
|
||
|
|
||
|
! Modification of prev_energy in function of rho
|
||
|
if (rho < thresh_rho) then !0.1) then
|
||
|
! the step is cancelled
|
||
|
print*, 'Rho <', thresh_rho,', the previous energy does not changed'
|
||
|
!print*, 'prev_energy :', prev_energy
|
||
|
else
|
||
|
! the step is accepted
|
||
|
prev_energy = energy
|
||
|
print*, 'Rho >=', thresh_rho,', energy -> prev_energy:', energy
|
||
|
endif
|
||
|
|
||
|
!call wall_time(t2)
|
||
|
!t3 = t2 - t1
|
||
|
!print*,'Time in rho model:', t3
|
||
|
|
||
|
print*,'---End rho_model---'
|
||
|
|
||
|
end subroutine
|
||
|
#+END_SRC
|