fix build on older gcc

CHANGELOG.rst

@@ -73,6 +73,7 @@ Version 2021-dev
 -  Fixed boost test deprecation warnings (#569)
 -  Refactored CUDA-OpenMP integration (#571)
 -  improved kmc output (#574)
+-  fix build on Ubuntu 16.04 (#577)
 
 Version 1.6.3 (released XX.08.20)
 =================================

include/votca/xtp/molden.h

@@ -49,20 +49,20 @@ class Molden {
  private:
   // clang-format off
   Logger& _log;
-  std::array<Index,25> _multipliers={
+  std::array<Index,25> _multipliers={{
             1, //s
             1,1,1, //p
             1,1,1,1,1, //d
             1,1,1,1,1,-1,-1, //f 
             1,1,1,1,1,-1,-1,-1,-1 //g
-            };
-  std::array<Index, 25> _reorderList={
+            }};
+  std::array<Index, 25> _reorderList={{
             0, //s
             1,-1,0, //p
             0,1,-1,2,-2, //d
             0,1,-1,2,-2,3,-3, //f 
             0,1,-1,2,-2,3,-3,4,-4 //g
-            };
+            }};
   // clang-format on
   std::string _basisset_name;
   std::string _aux_basisset_name;
@@ -80,4 +80,4 @@ class Molden {
 }  // namespace xtp
 }  // namespace votca
 
-#endif  // VOTCA_XTP_MOLDEN_WRITER_H
+#endif  // VOTCA_XTP_MOLDEN_WRITER_H

include/votca/xtp/orbreorder.h

@@ -50,13 +50,13 @@ class OrbReorder {
   std::array<Index, 25> _reorder;
   // clang-format off
   // the ordering of the m quantumnumbers for every shell
-  std::array<Index, 25> _votcaOrder={
+  std::array<Index, 25> _votcaOrder={{
             0, //s
             0,-1,1, //p
             0,-1,1,-2,2, //d
             0,-1,1,-2,2,-3,3, //f 
             0,-1,1,-2,2,-3,3,-4,4 //g
-            };
+            }};
   // clang-format on
   OrbTranspositions _transpositions;
 
@@ -69,4 +69,4 @@ class OrbReorder {
 }  // namespace xtp
 }  // namespace votca
 
-#endif  // VOTCA_XTP_ORBREODER_H
+#endif  // VOTCA_XTP_ORBREODER_H

src/libxtp/qmpackages/orca.h

@@ -69,20 +69,20 @@ class Orca : public QMPackage {
 
  private:
   // clang-format off
-  std::array<Index,25> _multipliers={
+  std::array<Index,25> _multipliers={{
             1, //s
             1,1,1, //p
             1,1,1,1,1, //d
             1,1,1,1,1,-1,-1, //f 
             1,1,1,1,1,-1,-1,-1,-1 //g
-            };
-  std::array<Index, 25> _reorderList={
+            }};
+  std::array<Index, 25> _reorderList={{
             0, //s
             0, 1,-1, //p
             0,1,-1,2,-2, //d
             0,1,-1,2,-2,3,-3, //f 
             0,1,-1,2,-2,3,-3,4,-4 //g
-            };
+            }};
 
   // clang-format on
   std::string indent(const double& number);

src/libxtp/qmpackages/xtpdft.h

@@ -78,20 +78,20 @@ class XTPDFT : public QMPackage {
 
  private:
   // clang-format off
-  std::array<Index,25> _multipliers={
+  std::array<Index,25> _multipliers={{
             1, //s
             1,1,1, //p
             1,1,1,1,1, //d
             1,1,1,1,1,1,1, //f 
             1,1,1,1,1,1,1,1,1 //g
-            };
-  std::array<Index,25> _reorderList={
+            }};
+  std::array<Index,25> _reorderList={{
             0, //s
             0,-1,1, //p
             0,-1,1,-2,2, //d
             0,-1,1,-2,2,-3,3, //f 
             0,-1,1,-2,2,-3,3,-4,4 //g
-            };
+            }};
   // clang-format on
 
   void WriteChargeOption() final { return; }