Add function to rotate vibrational Hamiltonian to VSCF basis (#6688)

**Context:**
Added functionality to rotate vibrational Hamiltonian integrals to VSCF
basis

**Description of the Change:**

**Benefits:**

**Possible Drawbacks:**

**Related GitHub Issues:**

[sc-80080]

---------

Co-authored-by: Soran Jahangiri <40344468+soranjh@users.noreply.github.com>
Co-authored-by: Austin Huang <65315367+austingmhuang@users.noreply.github.com>

doc/releases/changelog-dev.md

@@ -204,6 +204,8 @@ such as `shots`, `rng` and `prng_key`.
   * Implemented wrapper function for vibrational Hamiltonian calculation and dataclass
     for storing the data.
     [(#6652)](https://github.com/PennyLaneAI/pennylane/pull/6652)
+  * Implemented functions for generating the vibrational Hamiltonian in VSCF basis
+    [(#6688)](https://github.com/PennyLaneAI/pennylane/pull/6688)
 
 <h3>Improvements 🛠</h3>
 

pennylane/qchem/__init__.py

@@ -90,4 +90,5 @@
     taylor_coeffs,
     taylor_dipole_coeffs,
     taylor_hamiltonian,
+    vscf_integrals,
 )

pennylane/qchem/vibrational/__init__.py

@@ -1,3 +1,16 @@
+# Copyright 2018-2024 Xanadu Quantum Technologies Inc.
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 """
 This submodule provides the functionality to calculate vibrational Hamiltonians.
 """
@@ -10,3 +23,4 @@
 )
 from .localize_modes import localize_normal_modes
 from .vibrational_class import VibrationalPES, optimize_geometry
+from .vscf import vscf_integrals