SpinhalfDistributed

A block in a spin \(S=1/2\) Hilbert space with distributed computing capabilities.

Sources: spinhalf_distributed.hpp · spinhalf_distributed.cpp

Constructors

C++

SpinhalfDistributed(int64_t nsites, int64_t nup);

Name	Description	Default
nsites	number of sites (integer)
nup	number of "up" spin setting spin (integer)

Local configurations and operators

A SpinhalfDistributed block describes the same local Hilbert space as the shared-memory Spinhalf block, only the basis states are distributed across MPI processes. The local configuration encoding (0 = ↓, 1 = ↑) is therefore identical to the Spinhalf block.

Unlike the shared-memory block, the distributed block only supports the operators that have a dedicated distributed kernel. These are:

Sz, S+, S-, SzSz, Exchange, ExchangeAsym, and Id.

Their definitions are given in the Spinhalf operators table.

Iteration

An SpinhalfDistributed block can be iterated over, where at each iteration a ProductState representing the corresponding basis state is returned.

C++

auto block = SpinhalfDistributed(4, 2);
for (auto pstate : block) {
  Log("{} {}", to_string(pstate), block.index(pstate));
}

Methods

index

Returns the index of a given ProductState in the basis of the SpinhalfDistributed block.

C++

int64_t SpinhalfDistributed::index(ProductState const &pstate);

nsites

Returns the number of sites of the block.

C++

int64_t nsites(SpinhalfDistributed const &block);

size

Returns the size of the block on a local process.

C++

int64_t size(SpinhalfDistributed const &block) const;

dim

Returns the dimension of the block, i.e. the sum of all sizes across all processes.

C++

int64_t dim(SpinhalfDistributed const &block) const;

isreal

Returns whether the block can be used with real arithmetic. Complex arithmetic is needed when a Representation is genuinely complex.

C++

bool isreal(SpinhalfDistributed const &block);