add from_mol in HEA

Author: liwt31

tencirchem/static/hea.py

@@ -13,7 +13,7 @@
 import numpy as np
 from scipy.optimize import minimize
 from noisyopt import minimizeSPSA
-
+from pyscf.gto.mole import Mole
 from openfermion import (
  hermitian_conjugated,
  jordan_wigner,
@@ -186,6 +186,36 @@ class HEA:
  For a comprehensive tutorial see :doc:`/tutorial_jupyter/noisy_simulation`.
  """
 
+ @classmethod
+ def from_molecule(cls, m: Mole, n_layers=3, mapping="parity", **kwargs):
+ """
+ Construct the HEA class from the given molecule.
+ The :math:`R_y` ansatz is employed.
+
+
+ Parameters
+ ----------
+ m: Mole
+ The molecule object.
+ n_layers: int
+ The number of layers in the :math:`R_y` ansatz.
+ mapping: str
+ The fermion to qubit mapping. Supported mappings are ``"parity"``,
+ and ``"bravyi-kitaev"``.
+
+ kwargs:
+ Other arguments to be passed to the :func:`__init__` function such as ``engine``.
+
+ Returns
+ -------
+ hea: :class:`HEA`
+ An HEA instance
+ """
+ from tencirchem import UCC
+
+ ucc = UCC(m)
+ return cls.ry(ucc.int1e, ucc.int2e, ucc.n_elec, ucc.e_core, n_layers=n_layers, mapping=mapping, **kwargs)
+
  @classmethod
  def ry(
  cls,
@@ -198,10 +228,24 @@ def ry(
  mapping: str = "parity",
  **kwargs,
  ):
- """
- Construct the HEA class from electron integrals and custom quantum circuit.
+ r"""
+ Construct the HEA class from electron integrals and the :math:`R_y` ansatz.
+ The circuit consists of interleaved layers of $R_y$ and CNOT gates
+
+ .. math::
+
+ |\Psi(\theta)\rangle=\prod_{l=k}^1\left [ L_{R_y}^{(l)}(\theta) L_{CNOT}^{(l)} \right ] L_{R_y}^{(0)}(\theta) |{\phi}\rangle
+
+ where $k$ is the total number of layers, and the layers are defined as
+
+ .. math::
+ L_{CNOT}^{(l)}=\prod_{j=N/2-1}^1 CNOT_{2j, 2j+1} \prod_{j=N/2}^{1} CNOT_{2j-1, 2j}
+
+ .. math::
+ L_{R_y}^{(l)}(\theta)=\prod_{j=N}^{1} RY_{j}(\theta_{lj})
+
  Overlap integral is assumed to be identity.
- Parity transformation is used to transform from fermion operators to qubit operators.
+ Parity transformation is used to transform from fermion operators to qubit operators by default.
 
  Parameters
  ----------
@@ -216,8 +260,7 @@ def ry(
  n_layers: int
  The number of layers in the ansatz.
  init_circuit: Circuit
- The initial circuit before the :math:`R_y` ansatz. Defaults to None,
- which creates an HF initial state.
+ The initial circuit before the :math:`R_y` ansatz. Defaults to None.
  mapping: str
  The fermion to qubit mapping. Supported mappings are ``"parity"``,
  and ``"bravyi-kitaev"``.