colbert-ir/colbertv2.0 · BEIR Exp. NFCORPUS with colbertv2.0

I ran the BEIR experiments in this repo.
It reproduced the numbers in the paper with the checkpoint file "msmarco.psg.l2/checkpoints/colbert-300000.dnn".

Then, I save a dnn file for colbertv2.0 with codes below:

import torch
from transformers import AutoModel, AutoTokenizer

model_name = "colbert-ir/colbertv2.0"
tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModel.from_pretrained(model_name)

checkpoint = {
    'epoch': 0,
    'batch': 0,
    'model_state_dict': model.state_dict(),
    # 'optimizer_state_dict': optimizer.state_dict(),
    # 'arguments': {}
}
torch.save(checkpoint, "colbertv2.dnn")

It can still run but the result is completely broken.
NDCG@10 = 0.009

Did I miss something?

Thanks.