diff --git a/pyscf_ipu/experimental/nuclear_gradients.py b/pyscf_ipu/experimental/nuclear_gradients.py
index e01976a..e72b881 100644
--- a/pyscf_ipu/experimental/nuclear_gradients.py
+++ b/pyscf_ipu/experimental/nuclear_gradients.py
@@ -36,13 +36,9 @@ def grad_primitive_integral(
         Float3: Gradient of the integral with respect to cartesian axes.
     """
 
-    axes = jnp.arange(3)
-    lhs_p1 = vmap(a.offset_lmn, (0, None))(axes, 1)
-    t1 = 2 * a.alpha * vmap(primitive_op, (0, None))(lhs_p1, b)
-
-    lhs_m1 = vmap(a.offset_lmn, (0, None))(axes, -1)
-    t2 = a.lmn * vmap(primitive_op, (0, None))(lhs_m1, b)
-    grad_out = t1 - t2
+    t1 = [primitive_op(a.offset_lmn(ax, 1), b) for ax in range(3)]
+    t2 = [primitive_op(a.offset_lmn(ax, -1), b) for ax in range(3)]
+    grad_out = 2 * a.alpha * jnp.stack(t1) - a.lmn * jnp.stack(t2)
     return grad_out