It seems to me that you have redundant variables. Instead of five {A, B, C1, D1, \[Delta]}
you can manage with three x,y,z
, with much simpler formulas:
eqs0 = {m1 + m2 + (6 A)/\[Delta]^2 + (
3 B)/\[Delta] - (2 \[Mu])/
hbar^2 ((C1 + (8 A)/\[Delta]^3 + (3 B)/\[Delta]^2)/(
3 +
Sqrt[(8 \[Mu])/
hbar^2 (B/\[Delta]^3 + (3 A)/\[Delta]^4 - D1 +
hbar^2/(2 \[Mu]) (0 + 0.5)^2)]))^2 == 3.097,
m1 + m2 + (6 A)/\[Delta]^2 + (
3 B)/\[Delta] - (2 \[Mu])/
hbar^2 ((C1 + (8 A)/\[Delta]^3 + (3 B)/\[Delta]^2)/(
5 +
Sqrt[(8 \[Mu])/
hbar^2 (B/\[Delta]^3 + (3 A)/\[Delta]^4 - D1 +
hbar^2/(2 \[Mu]) (0 + 0.5)^2)]))^2 == 3.686,
m1 + m2 + (6 A)/\[Delta]^2 + (
3 B)/\[Delta] - (2 \[Mu])/
hbar^2 ((C1 + (8 A)/\[Delta]^3 + (3 B)/\[Delta]^2)/(
7 +
Sqrt[(8 \[Mu])/
hbar^2 (B/\[Delta]^3 + (3 A)/\[Delta]^4 - D1 +
hbar^2/(2 \[Mu]) (0 + 0.5)^2)]))^2 == 4.039,
m1 + m2 + (6 A)/\[Delta]^2 + (
3 B)/\[Delta] - (2 \[Mu])/
hbar^2 ((C1 + (8 A)/\[Delta]^3 + (3 B)/\[Delta]^2)/(
3 +
Sqrt[(8 \[Mu])/
hbar^2 (B/\[Delta]^3 + (3 A)/\[Delta]^4 - D1 +
hbar^2/(2 \[Mu]) (1 + 0.5)^2)]))^2 == 3.511,
m1 + m2 + (6 A)/\[Delta]^2 + (
3 B)/\[Delta] - (2 \[Mu])/
hbar^2 ((C1 + (8 A)/\[Delta]^3 + (3 B)/\[Delta]^2)/(
5 +
Sqrt[(8 \[Mu])/
hbar^2 (B/\[Delta]^3 + (3 A)/\[Delta]^4 - D1 +
hbar^2/(2 \[Mu]) (1 + 0.5)^2)]))^2 == 3.927,
m1 + m2 + (6 A)/\[Delta]^2 + (
3 B)/\[Delta] - (2 \[Mu])/
hbar^2 ((C1 + (8 A)/\[Delta]^3 + (3 B)/\[Delta]^2)/(
3 +
Sqrt[(8 \[Mu])/
hbar^2 (B/\[Delta]^3 + (3 A)/\[Delta]^4 - D1 +
hbar^2/(2 \[Mu]) (2 + 0.5)^2)]))^2 == 3.77};
eqsNew =
eqs0 /. {(C1 + (8 A)/\[Delta]^3 + (3 B)/\[Delta]^2)^2 -> x} /. {(
6 A)/\[Delta]^2 + (3 B)/\[Delta] -> y} /. {-D1 + (
3 A)/\[Delta]^4 + B/\[Delta]^3 -> z}
Solve[eqsNew, {x, y, z}]