Index: overlap.py
===================================================================
--- overlap.py	(revision 5164)
+++ overlap.py	(working copy)
@@ -58,7 +58,7 @@
 from gpaw.utilities.blas import gemm
 from gpaw import extra_parameters
 
-UL='U'
+UL = 'L'
 
 # Generate the coefficients for the Fourier-Bessel transform
 C = []
@@ -389,6 +389,12 @@
             yield a2, a1, -R_c, -offset
 
 
+class OppositeDirection(PairFilter):
+    def iter(self):
+        for a1, a2, R_c, offset in self.pairs.iter():
+            yield a2, a1, -R_c, -offset
+
+
 class FourierTransformer:
     def __init__(self, rcmax, ng):
         self.ng = ng
@@ -690,7 +696,7 @@
         expansions.append(ManySiteDictionaryWrapper(self.P_expansions,
                                                     P_aqxMi))
         arrays = [Theta_qxMM, T_qxMM, P_aqxMi]
-        calc.calculate(self.atompairs, expansions, arrays)
+        calc.calculate(OppositeDirection(self.atompairs), expansions, arrays)
 
     def evaluate(self, spos_ac, Theta_qMM, T_qMM, P_aqMi):
         calc = TwoCenterIntegralCalculator(self.ibzk_qc, derivative=False)