https://github.com/ITensor/ITensor
Tip revision: 7e0c480d71533289c95c67315b8c81cd1e2fed74 authored by Matthew Fishman on 18 October 2018, 18:22:10 UTC
Change *.ih -> *_impl.h
Change *.ih -> *_impl.h
Tip revision: 7e0c480
mpo_test.cc
#include "test.h"
#include "itensor/mps/mpo.h"
#include "itensor/mps/sites/spinhalf.h"
#include "itensor/mps/sites/spinone.h"
#include "itensor/util/print_macro.h"
#include "itensor/mps/sites/hubbard.h"
#include "itensor/mps/autompo.h"
using namespace itensor;
using namespace std;
TEST_CASE("MPOTest")
{
SECTION("Orthogonalize")
{
auto N = 10;
auto m = 4;
auto sites = SpinHalf(10);
auto W = MPO(sites);
//Make a random MPS of bond dim. m
auto links = vector<Index>(N+1);
for(auto n : range1(N))
{
links.at(n) = Index(nameint("l",n),m);
}
W.Aref(1) = randomTensor(links.at(1),sites(1),prime(sites(1)));
for(auto n : range1(2,N-1))
{
W.Aref(n) = randomTensor(links.at(n-1),sites(n),prime(sites(n)),links.at(n));
}
W.Aref(N) = randomTensor(links.at(N-1),sites(N),prime(sites(N)));
//Normalize W
auto n2 = overlap(W,W);
W.Aref(1) /= sqrt(n2);
auto oW = W;
W.orthogonalize();
CHECK_CLOSE(overlap(oW,W),1.0);
for(int n = N; n > 1; --n)
{
auto li = commonIndex(W.A(n),W.A(n-1),Link);
auto rho = W.A(n) * dag(prime(W.A(n),li));
auto id = ITensor(li,prime(li));
for(auto l : range1(li.m()))
{
id.set(li(l),prime(li)(l),1.0);
}
CHECK(norm(rho-id) < 1E-10);
}
}
SECTION("Add MPOs")
{
auto N = 50;
auto sites = Hubbard(N);
auto makeInds = [N](std::string name) -> vector<IQIndex>
{
auto ll = vector<IQIndex>(N);
for(auto n : range1(N-1))
{
ll.at(n) = IQIndex(nameint(name,n),
Index("a",2),QN("Sz=",-1,"Nf=",-1),
Index("a",2),QN("Sz=",-1,"Nf=",+1),
Index("b",2),QN("Sz=",-1,"Nf=",0),
Index("c",2),QN("Sz=",+1,"Nf=",0),
Index("d",2),QN("Sz=",+1,"Nf=",-1),
Index("d",2),QN("Sz=",+1,"Nf=",+1));
}
return ll;
};
auto l1 = makeInds("I1_");
auto l2 = makeInds("I2_");
auto Z = QN("Sz=",0,"Nf=",0);
auto A = IQMPO(sites);
auto B = IQMPO(sites);
A.Aref(1) = randomTensor(Z,sites(1),l1.at(1));
B.Aref(1) = randomTensor(Z,sites(1),l2.at(1));
for(int n = 2; n < N; ++n)
{
A.Aref(n) = randomTensor(Z,sites(n),dag(l1.at(n-1)),l1.at(n));
B.Aref(n) = randomTensor(Z,sites(n),dag(l2.at(n-1)),l2.at(n));
}
A.Aref(N) = randomTensor(Z,sites(N),dag(l1.at(N-1)));
B.Aref(N) = randomTensor(Z,sites(N),dag(l2.at(N-1)));
auto C = sum(A,B);
auto AA = overlap(A,A);
auto AB = overlap(A,B);
auto AC = overlap(A,C);
auto BB = overlap(B,B);
auto BC = overlap(B,C);
auto CC = overlap(C,C);
// |(A+B)-C|^2 = (A+B-C)*(A+B-C) = A*A+2A*B-2A*C+B*B-2B*C+C*C
auto diff2 = AA+2*AB-2*AC+BB-2*BC+CC;
CHECK(diff2 < 1E-12);
}
SECTION("Regression Test")
{
auto sites = Hubbard(2);
auto A = IQMPO(sites);
auto Ia = IQIndex("I",Index("1",2),QN("Sz",1,"Nf",-1),
Index("1",1),QN("Sz",-1,"Nf",-1));
A.Aref(1) = randomTensor(QN("Sz",-1,"Nf",1), prime(sites(1)), dag(Ia), dag(sites(1)));
A.Aref(2) = randomTensor(QN("Sz",1,"Nf",-1), Ia, dag(sites(2)), prime(sites(2)));
auto B = IQMPO(sites);
auto Ib = IQIndex("I",Index("1",2),QN("Sz",1,"Nf",-1),
Index("1",1),QN("Sz",-1,"Nf",-1));
B.Aref(1) = randomTensor(QN("Sz",0,"Nf",0), prime(sites(1)), dag(Ib), dag(sites(1)));
B.Aref(2) = randomTensor(QN("Sz",0,"Nf",0), prime(sites(2)), Ib, dag(sites(2)));
REQUIRE_NOTHROW(A.plusEq(B));
}
SECTION("applyMPO (DensityMatrix)")
{
auto method = "DensityMatrix";
auto N = 10;
auto sites = SpinHalf(N);
auto psi = MPS(sites);
//Use AutoMPO as a trick to get
//an MPO with bond dimension > 1
auto ampo = AutoMPO(sites);
for(auto j : range1(N-1))
{
ampo += "Sz",j,"Sz",j+1;
ampo += 0.5,"S+",j,"S-",j+1;
ampo += 0.5,"S-",j,"S+",j+1;
}
auto H = MPO(ampo);
auto K = MPO(ampo);
//Randomize the MPOs to make sure they are non-Hermitian
for(auto j : range1(N))
{
randomize(H.Aref(j));
randomize(K.Aref(j));
H.Aref(j) *= 0.2;
K.Aref(j) *= 0.2;
}
// Apply K to psi to entangle psi
psi = applyMPO(K,psi,{"Cutoff=",0.,"Maxm=",100});
psi /= norm(psi);
auto Hpsi = applyMPO(H,psi,{"Method=",method,"Cutoff=",1E-13,"Maxm=",5000});
CHECK_CLOSE(checkMPOProd(Hpsi,H,psi),0.);
}
SECTION("applyMPO (Fit)")
{
auto method = "Fit";
auto N = 10;
auto sites = SpinHalf(N);
auto psi = MPS(sites);
//Use AutoMPO as a trick to get
//an MPO with bond dimension > 1
auto ampo = AutoMPO(sites);
for(auto j : range1(N-1))
{
ampo += "Sz",j,"Sz",j+1;
ampo += 0.5,"S+",j,"S-",j+1;
ampo += 0.5,"S-",j,"S+",j+1;
}
auto H = MPO(ampo);
auto K = MPO(ampo);
//Randomize the MPOs to make sure they are non-Hermitian
for(auto j : range1(N))
{
randomize(H.Aref(j));
randomize(K.Aref(j));
H.Aref(j) *= 0.2;
K.Aref(j) *= 0.2;
}
// Apply K to psi to entangle psi
psi = applyMPO(K,psi,{"Cutoff=",0.,"Maxm=",100});
psi /= norm(psi);
auto Hpsi = applyMPO(H,psi,{"Method=",method,"Cutoff=",1E-13,"Maxm=",5000,"Sweeps=",100});
CHECK_CLOSE(checkMPOProd(Hpsi,H,psi),0.);
// Now with a trial starting state
auto Hpsi_2 = applyMPO(H,psi,Hpsi,{"Method=",method,"Cutoff=",1E-13,"Maxm=",5000,"Sweeps=",100});
CHECK_CLOSE(checkMPOProd(Hpsi_2,H,psi),0.);
}
SECTION("Overlap <psi|HK|phi>")
{
detail::seed_quickran(1);
auto N = 10;
auto sites = SpinHalf(N);
auto psi = MPS(sites);
auto phi = MPS(sites);
//Use AutoMPO as a trick to get
//an MPO with bond dimension > 1
auto ampo = AutoMPO(sites);
for(auto j : range1(N-1))
{
ampo += "Sz",j,"Sz",j+1;
ampo += 0.5,"S+",j,"S-",j+1;
ampo += 0.5,"S-",j,"S+",j+1;
}
auto H = MPO(ampo);
auto Hdag = H;
auto K = H;
//Randomize the MPOs to make sure they are non-Hermitian
for(auto j : range1(N))
{
randomize(H.Aref(j));
randomize(K.Aref(j));
H.Aref(j) *= 0.2;
K.Aref(j) *= 0.3;
Hdag.Aref(j) = dag(swapPrime(H.A(j),0,1,Site));
}
auto Hdphi = applyMPO(Hdag,phi,{"Cutoff=",1E-13,"Maxm=",5000,"Method=","DensityMatrix"});
auto Kpsi = applyMPO(K,psi,{"Cutoff=",1E-13,"Maxm=",5000,"Method=","DensityMatrix"});
//Print(overlap(phi,H,K,psi));
//Print(overlap(Hdphi,Kpsi));
CHECK_CLOSE(overlap(phi,H,K,psi),overlap(Hdphi,Kpsi));
}
SECTION("toMPO function")
{
auto N = 50;
auto sites = Hubbard(N);
auto makeInds = [N](std::string name) -> vector<IQIndex>
{
auto ll = vector<IQIndex>(N);
for(auto n : range1(N-1))
{
ll.at(n) = IQIndex(nameint(name,n),
Index("a",2),QN("Sz=",-1,"Nf=",-1),
Index("a",2),QN("Sz=",-1,"Nf=",+1),
Index("b",2),QN("Sz=",-1,"Nf=",0),
Index("c",2),QN("Sz=",+1,"Nf=",0),
Index("d",2),QN("Sz=",+1,"Nf=",-1),
Index("d",2),QN("Sz=",+1,"Nf=",+1));
}
return ll;
};
auto ll = makeInds("I_");
auto Z = QN("Sz=",0,"Nf=",0);
auto A = IQMPO(sites);
A.Aref(1) = randomTensor(Z,sites(1),ll.at(1));
for(int n = 2; n < N; ++n)
{
A.Aref(n) = randomTensor(Z,sites(n),dag(ll.at(n-1)),ll.at(n));
}
A.Aref(N) = randomTensor(Z,sites(N),dag(ll.at(N-1)));
auto a = toMPO(A);
for(auto n : range1(N))
{
CHECK(norm(a.A(n) - ITensor(A.A(n))) < 1E-10);
}
}
}