wrong bond_idx in mol center

[xxxlive]

the bond center index should be bond_idx + cand_offset. this may cause it can not get the right induced bond type change representation.

[ziqi92]

Thank you for your interest in our work and also thank you very much for pointing out this error!!

I have corrected the bond center index for bond type change prediction. I also double-checked the test code and found that the bond center index in the test function is correct. Please let me know if you have any questions or find any other problems.

Best,
Ziqi