# H.3 Hamiltonians

**URL:** <https://discuss.pennylane.ai/t/h-3-hamiltonians/1585>\
**Category:** Codebook\
**Created:** [December 29, 2021, 12:51am UTC](https://discuss.pennylane.ai/t/h-3-hamiltonians/1585 "2021-12-29T00:51:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![gidu](https://avatars.discourse-cdn.com/v4/letter/g/779978/32.png) [@gidu](https://discuss.pennylane.ai/u/gidu)\
**Post date:** [December 29, 2021, 12:51am UTC](https://discuss.pennylane.ai/t/h-3-hamiltonians/1585/1 "2021-12-29T00:51:07Z")

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I suspect this to be a typo or some oversight. The negative sign shouldn’t be there.

![image](https://canada1.discourse-cdn.com/flex012/uploads/pennylane/original/1X/92232bc9e435b3d9cef62eee9ce53a94417ee762.png)

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**Author:** ![Alvaro\_Ballon](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/alvaro_ballon/32/874_2.png) [@Alvaro\_Ballon](https://discuss.pennylane.ai/u/Alvaro_Ballon)\
**Post date:** [January 4, 2022, 10:33pm UTC](https://discuss.pennylane.ai/t/h-3-hamiltonians/1585/2 "2022-01-04T22:33:12Z")

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Thank you for this observation, you are completely right. If you have a Github account, I encourage you to submit this as an issue at [https://github.com/XanaduAI/Xanadu-Quantum-Codebook/issues](https://github.com/XanaduAI/Xanadu-Quantum-Codebook/issues). If you don’t have one, let me know and I can do it myself!