I think the extent of the war crimes they had committed by that point made a negotiated peace seem absolutely impossible to the German government. They had been fighting a war of extermination on the Eastern Front since June 1941, and had murdered or allowed to die millions of Soviet citizens (particularly Jews and POWs). They had already established the Operation Reinhardt death camps (Sobibor, Belzec, Treblinka) by early 1942, and had used Majdanek and Auschwitz II (Birkenau) as death camps. In other words, they would have been held accountable for enormous death and destruction directed particularly at civilians by the nations they were fighting. I cannot imagine that Germany could have negotiated a peace terms that they would have accepted. Even if the Nazi Party leaders had understood that the tide had definitively turned against them, which I do not think they did, the type of war they had chosen to wage up to that point made surrender a non-option.

Edited to add sources: Gita Sereny Into That Darkness- about Treblinka; Yitzhak Arad, Belzec, Sobibor, Treblinka: The Operation Reinhard Death Camps and The Holocaust in the Soviet Union; Waitman Beorn, Marching Into Darkness

Even if they had wanted to, it simply wasn't an option for them. President Roosevelt issued the Casablanca Declaration in January 1943, essentially saying the Allies would not make a negotiated peace with the Axis, that surrender must be unconditional.

The reason for this was the widely held belief that the Second World War was in part caused by the unsatisfactory end of the First World War.

Germany in 1918 was in bad shape, but they controlled huge swaths of Eastern Europe and on the Western Front were still fighting in France and Belgium. Many Germans believed that they hadn't really lost and all the problems of the 20's were due to new Republic surrendering to gain power.

In the Second World War Roosevelt was adamant this wouldn't happen again. The Germans would know, comprehensibly they had been defeated.

Even if the Nazis had tried to surrender, they would have almost certainly have been refused.

Exorcising Hitler - Fredrick Taylor, Savage Continent - Keith Lowe.