Going into a high-pressure negotiating situation, it makes sense to try to stay on an even keel: you're controlled, you're balanced, you're in charge of your emotions.
But a recent study from ESSEC, the University of Michigan, the University of Paris, and EMLYON, found that in certain situations, expressing sadness — and even tears — can apparently make you more likely to get what you want from the negotiation.
If your negotiating partner sees you as "low power," if they anticipate continued interactions with you, and if they see your relationship as collaborative, then it's possible that what Science Alert calls a "warranted display of pathos" could — maybe — get you what you your raise.
But even if it's true, it's very very very risky (do you really want to be seen as low power forever?). In the long run, it seems likely you'd be better off with a power pose, a well-chosen salary range, and a competitive spirit.