Update app_utils.py

app_utils.py

@@ -45,7 +45,7 @@ def initialize_knowledge_base():
     vStore = Chroma.from_documents(doc_texts, openAI_embeddings)
 
     conv_model = RetrievalQA.from_chain_type(
-        llm=OpenAI(), 
+        llm=OpenAI(model_name="gpt-3.5-turbo-16k"), 
         chain_type="stuff", 
         retriever=vStore.as_retriever(
             search_kwargs={"k": 1}