diff --git a/source/op/prod_virial_grad_multi_device.cc b/source/op/prod_virial_grad_multi_device.cc
index ac74d1d141..d8c8898c37 100644
--- a/source/op/prod_virial_grad_multi_device.cc
+++ b/source/op/prod_virial_grad_multi_device.cc
@@ -117,7 +117,7 @@ class ProdVirialSeAGradOp : public OpKernel
     // loop over frames
     for (int kk = 0; kk < nframes; ++kk){
       FPTYPE * grad_net = p_grad_net + kk * nloc * ndescrpt;
-      const FPTYPE * grad = p_grad + kk * nloc * 3;
+      const FPTYPE * grad = p_grad + kk * 9;
       const FPTYPE * in_deriv = p_in_deriv + kk * nloc * ndescrpt * 3;
       const FPTYPE * rij = p_rij + kk * nloc * nnei * 3;
       const int * nlist = p_nlist + kk * nloc * nnei; 
@@ -229,7 +229,7 @@ class ProdVirialSeRGradOp : public OpKernel
     // loop over frames
     for (int kk = 0; kk < nframes; ++kk){
       FPTYPE * grad_net = p_grad_net + kk * nloc * ndescrpt;
-      const FPTYPE * grad = p_grad + kk * nloc * 3;
+      const FPTYPE * grad = p_grad + kk * 9;
       const FPTYPE * in_deriv = p_in_deriv + kk * nloc * ndescrpt * 3;
       const FPTYPE * rij = p_rij + kk * nloc * nnei * 3;
       const int * nlist = p_nlist + kk * nloc * nnei; 
@@ -272,4 +272,4 @@ REGISTER_KERNEL_BUILDER(
     ProdVirialSeRGradOp<GPUDevice, T>);
 REGISTER_GPU(float);
 REGISTER_GPU(double);
-#endif  // GOOGLE_CUDA
\ No newline at end of file
+#endif  // GOOGLE_CUDA