FiniteMPS v1.7.1

Diff since v1.7.0

fix bug: MethodError when adding 4-site correlations to ObservableTree.

- Julia
Published by github-actions[bot] 7 months ago

FiniteMPS v1.7.0

Diff since v1.6.1

A stable version after merging a sequence of commits in dev branch.

Closed issues: - Unexpected Behavior in addIntr! When Handling Symmetric all-to-all Interactions (#11)

- Julia
Published by github-actions[bot] 7 months ago

FiniteMPS v1.6.1

Diff since v1.6.0

fix MethodError for LocalOperator + LocalOperator
update example

- Julia
Published by github-actions[bot] about 1 year ago

FiniteMPS v1.6.0

Diff since v1.5.0

Breaking changes

Rewrite addIntr! and addObs! and change the interface. For example, consider a hopping term, now the usage becomes julia addIntr!(Root, (Fdag, F), (i, j), (true, true), strength; Z = Z) where (true, true) means both operators are fermionic. Similarly, julia addObs!(Tree, (Fdag, F), (i, j), (true, true); Z = Z) for the calculation of single-particle correlations.
Now a multi-site correlation with duplicated site indices can automatically reduce to a shorter term. For example, in the case of $U1 \times SU2$ symmetry, the pairing correlation $\langle \Delta{12}^\dagger \Delta{23}\rangle$ can be simply calculated via julia addObs!(Tree, U1SUFermions.ΔₛdagΔₛ, (1, 2, 2, 3), (true, true, true, true); Z = U1SUFermions.Z)
Support adding 3-site terms, e.g. chiral operator $Si \cdot (Sj \times S_k)$ pinning field, to the Hamiltonian.

Merged pull requests: - ensure MPS used in calObs! is canonicalized at the first site (#7) (@phyjswang) - Add addIntr3! and U₁SU₂ operator SSS (#10) (@Asmendeus)

- Julia
Published by github-actions[bot] about 1 year ago

FiniteMPS v1.5.0

Diff since v1.4.2

New Features

Support the computation of imaginary-time proxy (ITP)

ITP forms like $\langle A(\beta/2) B\rangle_\beta = Z^{-1}{\rm Tr}\{e^{-\beta H/2} A e^{-\beta H/2} B\}$, which can be directly obtained with the thermal density operator $e^{-\beta H/2}$ represented as MPO. We provide the following interfaces for users.

A concrete type ImagTimeProxyGraph to describe the terms to be calculated.
addITP2! and addITP4! for adding terms like $\langle Ai(\beta/2) Bj\rangle\beta$ and $\langle Ai(\beta/2) Bj(\beta/2) Ck Dl \rangle\beta$, respectively.
merge! to compress the graph partially.
calITP! for in-place calculation.

Detailed usage please see the documentation via ? in REPL.

Example

The following shows a sample code for the calculation of the single particle Green's function $\langle ci^\dagger(\beta/2) cj\rangle\beta$ with $U1\times SU2$ symmetry. julia G = ImagTimeProxyGraph(L) for i in 1:L, j in i:L addITP2!(G, U1SU2Fermion.FdagF, (i, j), (:Fdag, :F); Z=U1SU2Fermion.Z) end merge!(G) calITP!(G, rho) where rho is a length-L MPO that represents $Z^{-1/2}e^{-\beta H/2}$. After this, the value of $\langle ci^\dagger(\beta/2) cj\rangle\beta$ is stored at julia G.Refs["FdagF"][(i, j)][]

There may exist bugs that have not yet been discovered, please check carefully with the results.

Other changes

Update dependent packages such as TensorKit.jl and KrylovKit.jl.

Closed issues: - ERROR: MethodError: Cannot convert an object of type ObservableTree{1} to an object of type Dict (#5)

- Julia
Published by github-actions[bot] over 1 year ago

FiniteMPS - v1.4.2

FiniteMPS v1.4.2

Diff since v1.4.1