def test_svd_compress(comp, mp):
if mp == "mpo":
mps = Mpo(holstein_model)
M = 22
else:
mps = Mps.random(holstein_model, 1, 10)
if mp == "mpdm":
mps = MpDm.from_mps(mps)
mps.canonicalise().normalize()
M = 36
if comp:
mps = mps.to_complex(inplace=True)
print(f"{mps}")
mpo = Mpo(holstein_model)
if comp:
mpo = mpo.scale(-1.0j)
print(f"{mpo.bond_dims}")
std_mps = mpo.apply(mps, canonicalise=True).canonicalise()
print(f"std_mps: {std_mps}")
mps.compress_config.bond_dim_max_value = M
mps.compress_config.criteria = CompressCriteria.fixed
svd_mps = mpo.contract(mps)
dis = svd_mps.distance(std_mps) / std_mps.dmrg_norm
print(f"svd_mps: {svd_mps}, dis: {dis}")
assert np.allclose(dis, 0.0, atol=1e-3)
assert np.allclose(svd_mps.dmrg_norm, std_mps.dmrg_norm, atol=1e-4)
def test_variational_compress(comp, mp):
if mp == "mpo":
mps = Mpo(holstein_model)
M = 20
else:
mps = Mps.random(holstein_model, 1, 10)
if mp == "mpdm":
mps = MpDm.from_mps(mps)
mps.canonicalise().normalize()
M = 36
if comp:
mps = mps.to_complex(inplace=True)
print(f"{mps}")
mpo = Mpo(holstein_model)
if comp:
mpo = mpo.scale(-1.0j)
print(f"{mpo.bond_dims}")
std_mps = mpo.apply(mps, canonicalise=True).canonicalise()
print(f"std_mps: {std_mps}")
# 2site algorithm
mps.compress_config.vprocedure = [[M, 1.0], [M, 0.2], [M, 0.1]] + [
[M, 0],
] * 10
mps.compress_config.vmethod = "2site"
var_mps = mps.variational_compress(mpo, guess=None)
dis = var_mps.distance(std_mps) / std_mps.dmrg_norm
print(f"var2_mps: {var_mps}, dis: {dis}")
assert np.allclose(dis, 0.0, atol=1e-4)
assert np.allclose(var_mps.dmrg_norm, std_mps.dmrg_norm, atol=1e-4)
# 1site algorithm with 2site result as a guess
# 1site algorithm is easy to be trapped in a local minimum
var_mps.compress_config.vprocedure = [
[M, 0],
] * 10
var_mps.compress_config.vmethod = "1site"
var_mps = mps.variational_compress(mpo, guess=var_mps)
dis = var_mps.distance(std_mps) / std_mps.dmrg_norm
print(f"var1_mps: {var_mps}, dis: {dis}")
assert np.allclose(dis, 0.0, atol=1e-4)
assert np.allclose(var_mps.dmrg_norm, std_mps.dmrg_norm, atol=1e-4)