Parameter: nflip
Definition
Flip period for spin up and spin down states.
Type
Integer
Default value
20000
Component
ALL, except for the DAISY component.
Behavior
Care must be taken to prevent the system from being trapped in a state which breaks a symmetry of local Hamiltonian when it should not be. To avoid un-physical trapping, we introduce "flip" moves, which exchange the operators corresponding, for example, to up and down spins in a given band.
In this code, nowadays the following flip schemes are supported:
cflip
= 1, flip inter-orbital spins randomly,cflip
= 2, flip intra-orbital spins one by one,cflip
= 3, flip intra-orbital spins globally.
Here cflip
is an internal variable, instead of an input parameters, you can not setup it in the solver.ctqmc.in file.
So the question is: how to control cflip
via the nflip parameter?
Now we use the sign of nflip to control flip schemes
nflip = 0, means infinite long period to do flip
nflip > 0, combine
cflip
= 2 (80%) andcflip
= 3 (20%)nflip < 0, combine
cflip
= 1 (80%) andcflip
= 3 (20%)
Comment
If nflip /= 0, the absolute value of nflip is the flip period.
When cflip = 1, the symmetry of all orbitals must be taken into consideration, otherwise the code may be trapped by a deadlock.