Dear all,
I am trying to solve the fermion hubbard model on a square lattice with a small cluster size of 2x2 using exact diagonalization. I want to look at the energy levels at half filling. I used to N_total parameter to fix the filling, but the energy levels results dont change if I change this parameter. Could you please help me with this problem? I have attached the param file that I used. I am using fulldiag of ALPS.
Regards Sriluckshmy
Dear Sriluckshmy,
The model "fermion Hubbard” only knows about Nup and Ndown quantum numbers. To conserve the total number of particles you should use the “alternative fermion Hubbard” model.
Best regards, Michele
-- ETH Zurich Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch www.itp.phys.ethz.ch
+41 44 633 78 56 phone +41 44 633 11 15 fax
On 30 Nov 2014, at 12:24, Sriluckshmy Viswanathan sriluckus@gmail.com wrote:
Dear all,
I am trying to solve the fermion hubbard model on a square lattice with a small cluster size of 2x2 using exact diagonalization. I want to look at the energy levels at half filling. I used to N_total parameter to fix the filling, but the energy levels results dont change if I change this parameter. Could you please help me with this problem? I have attached the param file that I used. I am using fulldiag of ALPS.
Regards Sriluckshmy
<ferm_hubbard>
Hi Michele,
Wow. That worked. Thank you so much.
On Sun, Nov 30, 2014 at 6:46 PM, Michele Dolfi dolfim@phys.ethz.ch wrote:
Dear Sriluckshmy,
The model "fermion Hubbard" only knows about Nup and Ndown quantum numbers. To conserve the total number of particles you should use the "alternative fermion Hubbard" model.
Best regards, Michele
-- ETH Zurich Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch www.itp.phys.ethz.ch
+41 44 633 78 56 phone +41 44 633 11 15 fax
On 30 Nov 2014, at 12:24, Sriluckshmy Viswanathan sriluckus@gmail.com
wrote:
Dear all,
I am trying to solve the fermion hubbard model on a square lattice with
a small cluster size of 2x2 using exact diagonalization. I want to look at the energy levels at half filling. I used to N_total parameter to fix the filling, but the energy levels results dont change if I change this parameter. Could you please help me with this problem? I have attached the param file that I used. I am using fulldiag of ALPS.
Regards Sriluckshmy
<ferm_hubbard>
Alternatively you can also define Nup_total and Ndown_total in the standard Hubbard model/
On 30 Nov 2014, at 14:28, Sriluckshmy Viswanathan sriluckus@gmail.com wrote:
Hi Michele,
Wow. That worked. Thank you so much.
On Sun, Nov 30, 2014 at 6:46 PM, Michele Dolfi <dolfim@phys.ethz.ch mailto:dolfim@phys.ethz.ch> wrote: Dear Sriluckshmy,
The model "fermion Hubbard” only knows about Nup and Ndown quantum numbers. To conserve the total number of particles you should use the “alternative fermion Hubbard” model.
Best regards, Michele
-- ETH Zurich Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch mailto:dolfim@phys.ethz.ch www.itp.phys.ethz.ch http://www.itp.phys.ethz.ch/
+41 44 633 78 56 tel:%2B41%2044%20633%2078%2056 phone +41 44 633 11 15 tel:%2B41%2044%20633%2011%2015 fax
On 30 Nov 2014, at 12:24, Sriluckshmy Viswanathan <sriluckus@gmail.com mailto:sriluckus@gmail.com> wrote:
Dear all,
I am trying to solve the fermion hubbard model on a square lattice with a small cluster size of 2x2 using exact diagonalization. I want to look at the energy levels at half filling. I used to N_total parameter to fix the filling, but the energy levels results dont change if I change this parameter. Could you please help me with this problem? I have attached the param file that I used. I am using fulldiag of ALPS.
Regards Sriluckshmy
<ferm_hubbard>
-- Regards Sriluckshmy
Hi,
Thank you so much for the help. That also worked. I was wondering if there was any method to measure four point correlation function (like <c_i^\dagger c_j c_k^\dagger c_l> for i,j,k,l all running over the lattice). I tried using fermion_hop as the two operators in MEASURE_CORRELATIONS but that didnt work. Could you please help me with this problem?
On Sun, Nov 30, 2014 at 10:26 PM, Matthias Troyer troyer@phys.ethz.ch wrote:
Alternatively you can also define Nup_total and Ndown_total in the standard Hubbard model/
On 30 Nov 2014, at 14:28, Sriluckshmy Viswanathan sriluckus@gmail.com wrote:
Hi Michele,
Wow. That worked. Thank you so much.
On Sun, Nov 30, 2014 at 6:46 PM, Michele Dolfi dolfim@phys.ethz.ch wrote:
Dear Sriluckshmy,
The model "fermion Hubbard" only knows about Nup and Ndown quantum numbers. To conserve the total number of particles you should use the "alternative fermion Hubbard" model.
Best regards, Michele
-- ETH Zurich Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch www.itp.phys.ethz.ch
+41 44 633 78 56 phone +41 44 633 11 15 fax
On 30 Nov 2014, at 12:24, Sriluckshmy Viswanathan sriluckus@gmail.com
wrote:
Dear all,
I am trying to solve the fermion hubbard model on a square lattice with
a small cluster size of 2x2 using exact diagonalization. I want to look at the energy levels at half filling. I used to N_total parameter to fix the filling, but the energy levels results dont change if I change this parameter. Could you please help me with this problem? I have attached the param file that I used. I am using fulldiag of ALPS.
Regards Sriluckshmy
<ferm_hubbard>
-- Regards Sriluckshmy
Hi,
ALPS does not currently support the measurement of 4-point functions. You could manually add it to the code.
Matthias
On 01 Dec 2014, at 05:17, Sriluckshmy Viswanathan sriluckus@gmail.com wrote:
Hi,
Thank you so much for the help. That also worked. I was wondering if there was any method to measure four point correlation function (like <c_i^\dagger c_j c_k^\dagger c_l> for i,j,k,l all running over the lattice). I tried using fermion_hop as the two operators in MEASURE_CORRELATIONS but that didnt work. Could you please help me with this problem?
On Sun, Nov 30, 2014 at 10:26 PM, Matthias Troyer <troyer@phys.ethz.ch mailto:troyer@phys.ethz.ch> wrote: Alternatively you can also define Nup_total and Ndown_total in the standard Hubbard model/
On 30 Nov 2014, at 14:28, Sriluckshmy Viswanathan <sriluckus@gmail.com mailto:sriluckus@gmail.com> wrote:
Hi Michele,
Wow. That worked. Thank you so much.
On Sun, Nov 30, 2014 at 6:46 PM, Michele Dolfi <dolfim@phys.ethz.ch mailto:dolfim@phys.ethz.ch> wrote: Dear Sriluckshmy,
The model "fermion Hubbard” only knows about Nup and Ndown quantum numbers. To conserve the total number of particles you should use the “alternative fermion Hubbard” model.
Best regards, Michele
-- ETH Zurich Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch mailto:dolfim@phys.ethz.ch www.itp.phys.ethz.ch http://www.itp.phys.ethz.ch/
+41 44 633 78 56 tel:%2B41%2044%20633%2078%2056 phone +41 44 633 11 15 tel:%2B41%2044%20633%2011%2015 fax
On 30 Nov 2014, at 12:24, Sriluckshmy Viswanathan <sriluckus@gmail.com mailto:sriluckus@gmail.com> wrote:
Dear all,
I am trying to solve the fermion hubbard model on a square lattice with a small cluster size of 2x2 using exact diagonalization. I want to look at the energy levels at half filling. I used to N_total parameter to fix the filling, but the energy levels results dont change if I change this parameter. Could you please help me with this problem? I have attached the param file that I used. I am using fulldiag of ALPS.
Regards Sriluckshmy
<ferm_hubbard>
-- Regards Sriluckshmy
-- Regards Sriluckshmy
comp-phys-alps-users@lists.phys.ethz.ch