diff --git a/src/molearn/data/prepare.py b/src/molearn/data/prepare.py
index 4bb4257..6d45bff 100644
--- a/src/molearn/data/prepare.py
+++ b/src/molearn/data/prepare.py
@@ -309,6 +309,41 @@ def distance_cluster(
         self._find_representatives(idx_idx, cluster_func.labels_)
         self.cluster_method = "CLUSTER_aggl"
 
+    def create_dendrogram(self, distance_threshold=50, output_path="dendrogram.png") -> None:
+        """
+        Cluster the trajectory with hierarchical clustering (linkage) based on the RMSD between the frames
+        and plot a dendrogram.
+        Group frames that have pairwise distances less than "distance_threshold" in one cluster (default is 50).
+        """
+        assert hasattr(
+            self, "traj_dists"
+        ), "No pairwise frame distances present - read in trajectory first"
+        
+        if self.verbose:
+            print("Hierarchical clustering")
+
+        # Perform hierarchical clustering using scipy
+        self.linkage_matrix = linkage(self.traj_dists, method="ward")  
+
+        # Plot the dendrogram
+        plt.figure(figsize=(10, 7))
+        dendrogram(self.linkage_matrix, no_labels=True, color_threshold=distance_threshold)
+        plt.title("Dendrogram of Frames")
+        plt.xlabel("Frame Index")
+        plt.ylabel("Distance")
+        plt.savefig('dendrogram.png')
+
+        # Define clusters by specifying n_clusters
+        self.cluster_labels = fcluster(self.linkage_matrix, t=distance_threshold, criterion="distance")
+
+        # Store cluster labels and representatives
+        idx_idx = np.arange(len(self.cluster_labels))
+        self._find_representatives(idx_idx, self.cluster_labels)
+        self.cluster_method = "CLUSTER_linkage"
+
+        if self.verbose:
+            print(f"Assigned {self.n_cluster} clusters.")
+
     def pca_cluster(self, n: int = 3) -> None:
         """
         cluster the trajectory with KMeans based on the first 5 principal components
@@ -455,6 +490,81 @@ def create_trajectories(
             self.traj[self.frame_idx[self.test_border :]].save_dcd(
                 os.path.join(self.outpath, f"./{self.traj_name}_test.dcd")
             )
+    
+    def create_trajectories_by_dendrogram(self, test_cluster: int) -> None:
+        """
+        Create test trajectories based on a specific cluster and create the train
+        trajectories from all the frames excluding the specific cluster.
+
+        :param int test_cluster: Cluster to use as the test set.
+        """
+        if self.test_size == 0.0:
+            raise ValueError("Test set is required to perform this operation.")
+
+        if self.cluster_labels is None:
+            raise ValueError(
+                "Cluster labels are not initialized. Please run create_dendrogram first."
+              )
+
+        assert all(
+            [
+                hasattr(self, "traj"),
+                hasattr(self, "traj_name"),
+                hasattr(self, "traj_dists"),
+                hasattr(self, "train_idx"),
+                hasattr(self, "frame_idx"),
+                hasattr(self, "cluster_idx"),            ]
+        ), "Ensure trajectory is clustered first"
+
+        # Get cluster labels
+        # cluster_labels = fcluster(linkage(self.traj_dists, method="ward"), t=self.n_cluster, criterion="maxclust")
+        self.unique_clusters = set(self.cluster_labels)
+
+
+        # Check if the test cluster is in the unique clusters
+        if test_cluster not in self.unique_clusters:
+            raise ValueError(f"Cluster {test_cluster} is not in the unique clusters.")
+
+        # Separate indices for train and test sets based on the cluster
+        test_cluster_indices = np.where(self.cluster_labels == test_cluster)[0]
+        train_cluster_indices = np.where(self.cluster_labels != test_cluster)[0]
+
+        if self.verbose:
+            print(f"Creating train and test trajectories with cluster {test_cluster} being the test set.")
+
+        # Save train trajectory
+        ori_frame_train_idx = self.train_idx[train_cluster_indices]
+        self._save_idx(
+            os.path.join(
+                self.outpath,
+                f"./{self.traj_name}_train_excluding_cluster_{test_cluster}_frames.txt",
+            ),
+            ori_frame_train_idx,
+        )
+        self.traj[ori_frame_train_idx].save_dcd(
+            os.path.join(
+                self.outpath, f"{self.traj_name}_train_excluding_cluster_{test_cluster}.dcd"
+            )
+        )
+
+        # Save test trajectory
+        ori_frame_test_idx = self.train_idx[test_cluster_indices]
+        self._save_idx(
+            os.path.join(
+                self.outpath,
+                f"./{self.traj_name}_test_cluster_{test_cluster}_frames.txt",
+            ),
+            ori_frame_test_idx,
+        )
+        self.traj[ori_frame_test_idx].save_dcd(
+            os.path.join(
+                self.outpath, f"{self.traj_name}_test_cluster_{test_cluster}.dcd"
+            )
+        )
+
+        if self.verbose:
+            print("Train and test trajectories successfully created.")
+
 
 
 if __name__ == "__main__":