quemb.molbe.sparse_2el_integral.SemiSparse3DTensor¶
- class quemb.molbe.sparse_2el_integral.SemiSparse3DTensor(unique_dense_data, shape, exch_reachable)¶
Special datastructure for semi-sparse and partially symmetric 3-indexed tensors.
For a tensor, \(T_{ijk}\), to be stored in this datastructure we assume
2-fold permutational symmetry for the \(i, j\) indices, i.e. \(T_{ijk} = T_{jik}\)
sparsity along the \(i, j\) indices, i.e. \(T_{ijk} = 0\) for many \(i, j\)
dense storage along the \(k\) index
It can be used for example to store the 3-center, 2-electron integrals \((\mu \nu | P)\), with AOs \(\mu, \nu\) and auxiliary basis indices \(P\). Semi-sparsely, because it is assumed that there are many exchange pairs \(\mu, \nu\) which are zero, while the integral along the auxiliary basis \(P\) is stored densely as numpy array.
2-fold permutational symmetry for the \(\mu, \nu\) pairs is assumed, i.e.
\[(\mu \nu | P) == (\nu, \mu | P)\]Note that this class is immutable which enables to store the unique, non-zero data in a dense manner, which has some performance benefits.
Attributes
- class_type = jitclass.SemiSparse3DTensor#7f01d31e27e0<_keys:array(int64, 1d, C),unique_dense_data:array(float64, 2d, C),shape:UniTuple(int64 x 3),exch_reachable:ListType[array(int64, 1d, C)],naux:int64>¶
Methods