ElectronDistributed

A block in an electron type Hilbert space, i.e. fermions with \(\uparrow, \downarrow\) spin with distributed computing capabilities.

Sources: electron_distributed.hpp · electron_distributed.cpp

Constructors

C++

ElectronDistributed(int64_t nsites, int64_t nup, int64_t ndn, std::string backend = "auto");

Name	Description	Default
nsites	number of sites (integer)
nup	number of "up" electrons (integer)
ndn	number of "dn" electrons (integer)

Local configurations and operators

An ElectronDistributed block describes the same local Hilbert space as the shared-memory Electron block, only the basis states are distributed across MPI processes. The local configuration encoding (0 = empty, 1 = ↑, 2 = ↓, 3 = ⇅) is therefore identical to the Electron block.

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

Cdagup, Cup, Cdagdn, Cdn, Hopup, Hopdn, HopupAsym, HopdnAsym, Nup, Ndn, Nupdn, NupNup, NupNdn, NdnNup, NdnNdn, NtotNtot, NupdnNupdn, HubbardU, SzSz, Exchange, ExchangeAsym, and Id.

Their definitions are given in the Electron operators table.

Iteration

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

C++

auto block = ElectronDistributed(4, 2, 1);
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 ElectronDistributed block.

C++

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

nsites

Returns the number of sites of the block.

C++

int64_t nsites(ElectronDistributed const &block);

size

Returns the size of the block on a local process.

C++

int64_t size(ElectronDistributed const &block) const;

dim

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

C++

int64_t dim(ElectronDistributed 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(ElectronDistributed const &block);