diff --git a/src/motions/bimodalangle.cpp b/src/motions/bimodalangle.cpp
index f3ea567..0ecbcae 100644
--- a/src/motions/bimodalangle.cpp
+++ b/src/motions/bimodalangle.cpp
@@ -37,7 +37,7 @@ namespace motions {
         auto parameter = BaseMotion::getParameters();
         parameter["angle1"] = m_angle1 * 180 / M_PI;
         parameter["angle2"] = m_angle2 * 180 / M_PI;
-        parameter["probality1"] = m_prob;
+        parameter["probability1"] = m_prob;
         return parameter;
     }
 
diff --git a/src/motions/sixsitejump.h b/src/motions/sixsitejump.h
index 314de74..d900b62 100644
--- a/src/motions/sixsitejump.h
+++ b/src/motions/sixsitejump.h
@@ -20,7 +20,7 @@ namespace motions {
         [[nodiscard]] std::string toString() const override;
 
     private:
-        double m_chi{0.95531661812450927816385710251575775424341469501000549095969812932191204590};  // 54.74 deg
+        double m_chi{std::acos(-1.0 / 3.0)};  // 54.74 deg
 
         std::array<double, 6> m_corners{};
         int m_corner_idx{0};
diff --git a/src/sims.cpp b/src/sims.cpp
index 1fb3b86..97bd071 100644
--- a/src/sims.cpp
+++ b/src/sims.cpp
@@ -9,12 +9,12 @@
 
 void run_simulation(
     Experiment& experiment,
-    std::unordered_map<std::string, double>& parameter,
-    std::unordered_map<std::string, double>& optional,
+    const std::unordered_map<std::string, double>& parameter,
+    const std::unordered_map<std::string, double>& optional,
     Dynamics& dynamics,
     std::mt19937_64& rng
     ) {
-    const int num_walker = static_cast<int>(parameter["num_walker"]);
+    const int num_walker = static_cast<int>(parameter.at("num_walker"));
 
     dynamics.setParameters(parameter);
     experiment.setup(parameter, optional);
@@ -107,7 +107,7 @@ Trajectory make_trajectory(
 }
 
 
-std::chrono::system_clock::time_point printStart(std::unordered_map<std::string, double> &optional) {
+std::chrono::system_clock::time_point printStart(const std::unordered_map<std::string, double> &optional) {
     const auto start = std::chrono::system_clock::now();
     const time_t start_time = std::chrono::system_clock::to_time_t(start);
 
diff --git a/src/sims.h b/src/sims.h
index eb96e7e..094ce07 100644
--- a/src/sims.h
+++ b/src/sims.h
@@ -11,14 +11,14 @@
 
 void run_simulation(
     Experiment& experiment,
-    std::unordered_map<std::string, double>& parameter,
-    std::unordered_map<std::string, double>& optional,
+    const std::unordered_map<std::string, double>& parameter,
+    const std::unordered_map<std::string, double>& optional,
     Dynamics& dynamics,
     std::mt19937_64& rng);
 
 Trajectory make_trajectory(Dynamics& dynamics, double t_max, std::mt19937_64& rng);
 
-std::chrono::system_clock::time_point printStart(std::unordered_map<std::string, double> &optional);
+std::chrono::system_clock::time_point printStart(const std::unordered_map<std::string, double> &optional);
 void printEnd(std::chrono::system_clock::time_point start);
 
 #endif //RWSIM_SIMS_H
diff --git a/src/utils/functions.cpp b/src/utils/functions.cpp
index beed0f8..2ff18e5 100644
--- a/src/utils/functions.cpp
+++ b/src/utils/functions.cpp
@@ -4,7 +4,8 @@
 
 
 int nearest_index(const std::vector<double> &x_ref, const double x, int start=0) {
-    while (x > x_ref[start+1]) {
+    const int last = static_cast<int>(x_ref.size()) - 2;
+    while (start < last && x > x_ref[start+1]) {
         start++;
     }
     return start;
diff --git a/src/utils/ranges.cpp b/src/utils/ranges.cpp
index 6d16e24..732c4f0 100644
--- a/src/utils/ranges.cpp
+++ b/src/utils/ranges.cpp
@@ -14,6 +14,7 @@ std::vector<double> arange(const int size, const double spacing=1.) {
 
 std::vector<double> linspace(const double start, const double stop, const int steps) {
     std::vector<double> range;
+    range.reserve(steps);
 
     if (steps == 0) {
         return range;
@@ -34,6 +35,7 @@ std::vector<double> linspace(const double start, const double stop, const int st
 
 std::vector<double> logspace(const double start, const double stop, const int steps) {
     std::vector<double> range;
+    range.reserve(steps);
 
     if (steps == 0) {
         return range;
@@ -49,7 +51,7 @@ std::vector<double> logspace(const double start, const double stop, const int st
 
     const double stepsize = (logstop-logstart) / (steps-1);
     for (int i=0; i<steps; i++) {
-        range.push_back(pow(10, logstart + stepsize * i));
+        range.push_back(std::pow(10, logstart + stepsize * i));
     }
     return range;
 }
\ No newline at end of file