From 96abbe86663b032f7ebbcc01439aa48557de8386 Mon Sep 17 00:00:00 2001
From: Geoff Hutchison <geoff.hutchison@gmail.com>
Date: Fri, 6 Dec 2024 16:02:53 -0500
Subject: [PATCH] Don't bother calculating dipole moments for empty or 1-atom
 mols

Signed-off-by: Geoff Hutchison <geoff.hutchison@gmail.com>
---
 avogadro/calc/chargemanager.cpp | 4 ++++
 avogadro/calc/chargemodel.cpp   | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/avogadro/calc/chargemanager.cpp b/avogadro/calc/chargemanager.cpp
index e4a397b869..21775a98b6 100644
--- a/avogadro/calc/chargemanager.cpp
+++ b/avogadro/calc/chargemanager.cpp
@@ -164,6 +164,10 @@ Vector3 ChargeManager::dipoleMoment(const std::string& identifier,
     return Vector3(0.0, 0.0, 0.0);
   }
 
+  if (molecule.atomCount() < 2) {
+    return Vector3(0.0, 0.0, 0.0);
+  }
+
   const auto id = m_identifiers[lowerId];
   const ChargeModel* model = m_models[id];
   return model->dipoleMoment(molecule);
diff --git a/avogadro/calc/chargemodel.cpp b/avogadro/calc/chargemodel.cpp
index 995aea758c..eedfd68fb9 100644
--- a/avogadro/calc/chargemodel.cpp
+++ b/avogadro/calc/chargemodel.cpp
@@ -23,6 +23,9 @@ constexpr double M_PI = 3.14159265358979323846;
 
 Vector3 ChargeModel::dipoleMoment(const Molecule& mol) const
 {
+  if (mol.atomCount() < 2)
+    return Vector3(0.0, 0.0, 0.0);
+
   // default is to get the set of partial atomic charges
   // (some models might do something more sophisticated)
   const MatrixX charges = partialCharges(mol);