Merge pull request #721 from edoapra/master

use dftd3 method to address zero small denominators

QA/doqmtests.mpi

@@ -586,6 +586,8 @@ let "myexit+=$?"
 let "myexit+=$?"
 ./runtests.mpi.unix procs $np h2o_ccca o2_ccca
 let "myexit+=$?"
+./runtests.mpi.unix procs $np dftd3_c6cn
+let "myexit+=$?"
 fi
 #--- if we only want quick tests get out now!
 if [[ "$what" == "fast" ]]; then

QA/tests/dftd3_c6cn/dftd3_c6cn.nw

@@ -0,0 +1,62 @@
+echo
+charge 0
+
+geometry noautoz
+O          0.92504        0.99938        2.07185
+O          1.68765        1.57908       -0.29568
+H          3.55204        2.68516        0.28628
+C          0.29661        0.89268        3.31517
+C          2.11209        1.80315        2.02170
+C          2.43675        2.01653        0.57987
+H          0.67784        1.56486        4.44460
+O         -1.08891       -0.62239        2.15648
+O         -1.72707       -1.54708       -0.16299
+H         -3.68169       -2.46110        0.48375
+C         -0.80690        0.02845        3.35278
+C         -2.33997       -1.33013        2.13140
+C         -2.56045       -1.79603        0.72196
+H         -1.50976       -0.14582        4.51669
+Ca         0.00000        0.00000        0.00000
+O         -0.92505        0.99938       -2.07185
+O         -1.68765        1.57908        0.29568
+H         -3.55205        2.68516       -0.28628
+C         -0.29662        0.89268       -3.31516
+C         -2.11210        1.80315       -2.02170
+C         -2.43676        2.01653       -0.57987
+H         -0.67784        1.56486       -4.44460
+O          1.08890       -0.62239       -2.15647
+O          1.72706       -1.54708        0.16299
+H          3.68169       -2.46110       -0.48374
+C          0.80690        0.02845       -3.35278
+C          2.33996       -1.33013       -2.13140
+C          2.56044       -1.79603       -0.72196
+H          1.50975       -0.14582       -4.51669
+H          2.97119        1.25775        2.53560
+H          1.91900        2.79894        2.54200
+H          1.85225        2.99521        0.59220
+H         -3.18534       -0.63249        2.44484
+H         -2.28804       -2.21902        2.84328
+H         -2.02490       -2.77456        0.95706
+H         -2.97119        1.25775       -2.53560
+H         -1.91901        2.79894       -2.54200
+H         -1.85225        2.99521       -0.59220
+H          3.18533       -0.63249       -2.44484
+H          2.28803       -2.21902       -2.84328
+H          2.02489       -2.77456       -0.95706
+
+end 
+
+basis "ao basis" spherical
+* library def2-svp
+end
+
+
+
+dft
+direct
+xc cpbe96 xpbe96
+adft
+disp vdw 4
+convergence fast
+end
+task dft