Dear Khalid,
The momenta correspond to Bloch waves with that momentum constructed from real space basis states.
Once you have a finite hopping or any quantum dynamics the eigenstates will never be simple states with localized particles, such as "at site 1 there is up, down or double occupied etc.", but will always be a superposition of such states.
Matthias
On 10 Jun 2009, at 12:18, khalid hassan wrote:
Dear alps team
for the exact diaginalization program fulldiag and sparsediag, the output is divided into total momentum quantum numbers. also in many papers the spectrum is shown according to total momentum quantum number.
for example for a square 2 by 2 lattice
the program output with fulldiag will be divided as
total momentum = 0 0
total momentum = Pi 0
total momentum = 0 Pi
total momentum = Pi Pi
Now i want to know that
is these are written in k-space as these are not possible in real space
how they correspond to the values in real space
for example
we have Nup and Ndown known as alps gives for a certain momentum eg Pi 0 can we know Nup and Ndown at each sites in real space
for example
for 3 up and 1 down in square lattice
can we know at site 1 there is up, down or double occupied etc. is there some program statement in alps that tells this
I also want to know the total spin S for each case in square lattice can alps helps.
alps web site says something about total momentum but everyone knows it I cant find my answers there.
actually I want the energies output by alps to correspong to situation in real space how can I associate these specific situations with these energies
best regards
khalid loane