Update basisset to use numpy over jax.numpy (#126)

* Update basisset to use numpy over jax.numpy

* change lmn to use signed int32

* use jnp in primitive product method to support jit

pyscf_ipu/experimental/basis.py

@@ -3,6 +3,7 @@
 
 import chex
 import jax.numpy as jnp
+import numpy as np
 
 from .orbital import Orbital
 from .structure import Structure
@@ -61,9 +62,9 @@ def basisset(structure: Structure, basis_name: str = "sto-3g"):
             for lmn in LMN_MAP[s["angular_momentum"][0]]:
                 ao = Orbital.from_bse(
                     center=center,
-                    alphas=jnp.array(s["exponents"], dtype=float),
-                    lmn=jnp.array(lmn, dtype=jnp.int32),
-                    coefficients=jnp.array(s["coefficients"], dtype=float),
+                    alphas=np.array(s["exponents"], dtype=np.float32),
+                    lmn=np.array(lmn, dtype=np.int32),
+                    coefficients=np.array(s["coefficients"], dtype=np.float32),
                 )
                 orbitals.append(ao)
 

pyscf_ipu/experimental/primitive.py

@@ -3,16 +3,17 @@
 
 import chex
 import jax.numpy as jnp
-from jax.scipy.special import gammaln
+import numpy as np
+from scipy.special import gammaln
 
 from .types import Float3, FloatN, FloatNx3, Int3
 
 
 @chex.dataclass
 class Primitive:
-    center: Float3 = jnp.zeros(3, dtype=jnp.float32)
+    center: Float3 = np.zeros(3, dtype=np.float32)
     alpha: float = 1.0
-    lmn: Int3 = jnp.zeros(3, dtype=jnp.int32)
+    lmn: Int3 = np.zeros(3, dtype=np.int32)
     norm: Optional[float] = None
 
     def __post_init__(self):
@@ -21,16 +22,16 @@ def __post_init__(self):
 
     @property
     def angular_momentum(self) -> int:
-        return jnp.sum(self.lmn)
+        return np.sum(self.lmn)
 
     def __call__(self, pos: FloatNx3) -> FloatN:
         return eval_primitive(self, pos)
 
 
 def normalize(lmn: Int3, alpha: float) -> float:
-    L = jnp.sum(lmn)
+    L = np.sum(lmn)
     N = ((1 / 2) / alpha) ** (L + 3 / 2)
-    N *= jnp.exp(jnp.sum(gammaln(lmn + 1 / 2)))
+    N *= np.exp(np.sum(gammaln(lmn + 1 / 2)))
     return N**-0.5
 
 

pyscf_ipu/experimental/structure.py

@@ -20,6 +20,9 @@ def __post_init__(self):
         if not self.is_bohr:
             self.position = to_bohr(self.position)
 
+        # single atom case
+        self.position = np.atleast_2d(self.position)
+
     @property
     def num_atoms(self) -> int:
         return len(self.atomic_number)