# Operator Library The C API provides various functions to simplify the construction of commonly used operators. ## Commutator Generators | [`qf_op_type_commutator()`](qf-commutators.html.md#c.qf_op_type_commutator) | Computes the commutator of two operators. | |----------------------------------------------------------------------------------------------------------------|----------------------------------------------------| | [`qf_op_type_anti_commutator()`](qf-commutators.html.md#c.qf_op_type_anti_commutator) | Computes the anti-commutator of two operators. | | [`qf_op_type_double_commutator()`](qf-commutators.html.md#c.qf_op_type_double_commutator) | Computes the double-commutator of three operators. | ## Common Operators This section provides a quick reference for various operator constructor functions, grouped by category. ### Electronic Integrals | [`qf_ferm_op_from_1body_tril_spin_sym()`](qf-electronic-integrals.html.md#c.qf_ferm_op_from_1body_tril_spin_sym) | Constructs from spin-symmetric triangular 1-body
integrals. | |--------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------| | [`qf_ferm_op_from_1body_tril_spin()`](qf-electronic-integrals.html.md#c.qf_ferm_op_from_1body_tril_spin) | Constructs from separate spin-species triangular
1-body integrals. | | [`qf_ferm_op_from_2body_tril_spin_sym()`](qf-electronic-integrals.html.md#c.qf_ferm_op_from_2body_tril_spin_sym) | Constructs from spin-symmetric triangular 2-body
integrals. | | [`qf_ferm_op_from_2body_tril_spin()`](qf-electronic-integrals.html.md#c.qf_ferm_op_from_2body_tril_spin) | Constructs from separate spin-species triangular
2-body integrals. | ## Other Generators Finally, the following additional operator generator utilities exist: | [`QfFCIDump`](qf-fcidump.html.md#c.QfFCIDump) | An electronic structure Hamiltonian in FCIDump format. | |--------------------------------------------------------------------------|----------------------------------------------------------|