diff --git a/src/molecules/mixingrules/LorentzBerthelot.cpp b/src/molecules/mixingrules/LorentzBerthelot.cpp
new file mode 100644
index 0000000000..5d58532a58
--- /dev/null
+++ b/src/molecules/mixingrules/LorentzBerthelot.cpp
@@ -0,0 +1,19 @@
+#include "LorentzBerthelot.h"
+
+#include <ostream>
+
+#include "MixingRuleBase.h"
+#include "utils/Logger.h"
+#include "utils/xmlfileUnits.h"
+
+void LorentzBerthelotMixingRule::readXML(const XMLfileUnits& xmlconfig) {
+	MixingRuleBase::readXML(xmlconfig);
+	double eta, xi;
+	xmlconfig.getNodeValue("eta", eta);
+	xmlconfig.getNodeValue("xi", xi);
+	_parameters = {eta, xi};
+	Log::global_log->info() << "Mixing coefficients for components "
+							<< this->getCid1()+1 << " + " << this->getCid2()+1  // +1 due to internal cid
+							<< ": (eta, xi) = (" << _parameters.at(0)
+							<< ", " <<  _parameters.at(1) << ")" << std::endl;
+}
diff --git a/src/molecules/mixingrules/LorentzBerthelot.h b/src/molecules/mixingrules/LorentzBerthelot.h
index 23e5ac598b..5eb4f51004 100644
--- a/src/molecules/mixingrules/LorentzBerthelot.h
+++ b/src/molecules/mixingrules/LorentzBerthelot.h
@@ -1,25 +1,15 @@
 #ifndef LORENTZBERTHELOT_H_
 #define LORENTZBERTHELOT_H_
 
-#include "molecules/mixingrules/MixingRuleBase.h"
+#include <string>
 
-#include "utils/Logger.h"
-#include "utils/xmlfileUnits.h"
+#include "MixingRuleBase.h"
+
+class XMLfileUnits;
 
 class LorentzBerthelotMixingRule : public MixingRuleBase {
-public:
-
-	void readXML(XMLfileUnits& xmlconfig) override {
-		MixingRuleBase::readXML(xmlconfig);
-		double eta, xi;
-		xmlconfig.getNodeValue("eta", eta);
-		xmlconfig.getNodeValue("xi", xi);
-		_parameters = {eta, xi};
-		Log::global_log->info() << "Mixing coefficients for components "
-								<< this->getCid1()+1 << " + " << this->getCid2()+1  // +1 due to internal cid
-								<< ": (eta, xi) = (" << _parameters.at(0)
-								<< ", " <<  _parameters.at(1) << ")" << std::endl;
-	}
+ public:
+	void readXML(const XMLfileUnits& xmlconfig) override;
 
 	// _parameters of MixingRuleBase.cpp contains (eta, xi) in case of this mixing rule
 	double getEta() const { return _parameters.at(0); }
@@ -28,8 +18,7 @@ class LorentzBerthelotMixingRule : public MixingRuleBase {
 	void setEta(double eta) { _parameters.at(0) = eta; }
 	void setXi(double xi) { _parameters.at(1) = xi; }
 
-	std::string getType() const override { return "LB"; };
-
+	std::string getType() const override { return "LB"; }
 };
 
 #endif /* LORENTZBERTHELOT_H_ */
diff --git a/src/molecules/mixingrules/MixingRuleBase.cpp b/src/molecules/mixingrules/MixingRuleBase.cpp
new file mode 100644
index 0000000000..7214c58a8d
--- /dev/null
+++ b/src/molecules/mixingrules/MixingRuleBase.cpp
@@ -0,0 +1,30 @@
+#include "MixingRuleBase.h"
+
+#include <ostream>
+
+#include "utils/Logger.h"
+#include "utils/mardyn_assert.h"
+#include "utils/xmlfileUnits.h"
+
+void MixingRuleBase::readXML(const XMLfileUnits& xmlconfig) {
+	int cid1;
+	int cid2;
+	xmlconfig.getNodeValue("@cid1", cid1);
+	xmlconfig.getNodeValue("@cid2", cid2);
+
+	if (cid1 == cid2) {
+		Log::global_log->error() << "Mixing rules: cid1 and cid2 must not be the same but are both " << cid1 << std::endl;
+		mardyn_exit(1);
+	} else if ((cid1 <= 0) or (cid2 <= 0)) {
+		Log::global_log->error() << "Mixing rules: cid1 and cid2 must be greater than zero" << std::endl;
+		mardyn_exit(1);
+	} else if (cid1 > cid2) {
+	// Symmetry for mixing rules is assumed
+	// cid1 must be less than cid2
+		_cid1 = cid2 - 1;  // component id - 1 to convert to internal format starting with 0
+		_cid2 = cid1 - 1;
+	} else {
+		_cid1 = cid1 - 1;
+		_cid2 = cid2 - 1;
+	}
+}
diff --git a/src/molecules/mixingrules/MixingRuleBase.h b/src/molecules/mixingrules/MixingRuleBase.h
index a3af7185ab..192d188a8f 100644
--- a/src/molecules/mixingrules/MixingRuleBase.h
+++ b/src/molecules/mixingrules/MixingRuleBase.h
@@ -2,36 +2,13 @@
 #define MIXINGRULE_BASE_H_
 
 #include <string>
+#include <vector>
 
-#include "utils/Logger.h"
-#include "utils/mardyn_assert.h"
-#include "utils/xmlfileUnits.h"
+class XMLfileUnits;
 
 class MixingRuleBase {
-public:
-
-	virtual void readXML(XMLfileUnits& xmlconfig) {
-		int cid1;
-		int cid2;
-		xmlconfig.getNodeValue("@cid1", cid1);
-		xmlconfig.getNodeValue("@cid2", cid2);
-
-		if (cid1 == cid2) {
-			Log::global_log->error() << "Mixing rules: cid1 and cid2 must not be the same but are both " << cid1 << std::endl;
-			mardyn_exit(1);
-		} else if ((cid1 <= 0) or (cid2 <= 0)) {
-			Log::global_log->error() << "Mixing rules: cid1 and cid2 must be greater than zero" << std::endl;
-			mardyn_exit(1);
-		} else if (cid1 > cid2) {
-		// Symmetry for mixing rules is assumed
-		// cid1 must be less than cid2
-			_cid1 = cid2 - 1;  // component id - 1 to convert to internal format starting with 0
-			_cid2 = cid1 - 1;
-		} else {
-			_cid1 = cid1 - 1;
-			_cid2 = cid2 - 1;
-		}
-	}
+ public:
+	virtual void readXML(const XMLfileUnits& xmlconfig);
 
 	int getCid1() const { return _cid1; }
 	int getCid2() const { return _cid2; }
@@ -41,14 +18,14 @@ class MixingRuleBase {
 
 	virtual std::string getType() const = 0;
 
-	const std::vector<double> &getParameters() const { return _parameters; };
-	void setParameters(std::vector<double> params) { _parameters = params; };
+	const std::vector<double> &getParameters() const { return _parameters; }
+	void setParameters(std::vector<double> params) { _parameters = params; }
 
 	// Parameters of mixing rule
 	// e.g. for LB it contains (eta, xi)
 	std::vector<double> _parameters {1.0, 1.0};  // default for eta, xi;
 
-private:
+ private:
 	// Internal cids starting with 0
 	int _cid1 {};
 	int _cid2 {};