Update app.py

app.py

@@ -153,7 +153,7 @@ llm = HuggingFaceHub(repo_id = llm_model,
                                   "load_in_8bit": True})
 retriever=vector_db.as_retriever()
 memory = ConversationBufferMemory(memory_key="chat_history", output_key='answer', return_messages=True)
-qa_chain = ConversationalRetrievalChain.from_llm(llm_model,retriever=retriever,chain_type="stuff", 
+qa_chain = ConversationalRetrievalChain.from_llm(llm,retriever=retriever,chain_type="stuff", 
                                                  memory=memory,return_source_documents=True,verbose=False,)
 
 print('qa chain and vector_db done')