Does anyone know about an anthem for the Empire?  I think they had one but I don't know.  It wouldn't have lasted long anyway since the Empire and Emperor (the former president) were unpopular and was forced to step down.

"1915年12月12日，袁世凯宣布接受帝位，改国号为“中华帝国”。接着，下令改民国五年为“洪宪元年”，准备于1916年元旦正式登极。可惜好梦不长。经过辛亥革命洗礼的人民决不允许帝制复辟，反袁、反日的爱国运动迅猛兴起。孙中山领导的中华革命党，公开号召人们“乘时奋起”，把反袁斗争进行到底。一向拥护袁世凯的进步党也走上反袁道路。连北洋军阀集团内部，也明显分化。没等袁世凯黄袍加身，云南蔡锷就发起护国运动，组织护国军讨伐袁世凯。
　　袁世凯在众叛亲离的情况下，只得于1916年3月22日宣布取消帝制，可还以大总统自居。但全国各地纷纷组织武装起义，挂起护国军的旗帜，要求惩办袁世凯。袁世凯恼羞成病，于1916年6月6日在全国人民的唾骂声中死去。"

This is an article from "People Daily".
Yuan Shikai declare to change the name of "Republic of China" into "Chinese Empire" on 12th, Dec., 1915. He want to be the king on 1st, Jan., 1916. But the anti-Yuan's army intimidate Yuan Shikai. He declare to abandon his empire on 22nd, March, 1916. But he was still the president. In the end, he died on 6th, June, 1916.

So this empire is from 12th, Dec., 1915 to 22nd, March, 1916, actually.