Actual Accounts of Thermopylae?

Thank you gentlemen for your considered responses, and in the end there isn't that much actual evidence from the time around and what exists is very biased to a Greek version of events.

Can I propose a very contentious variation.

Xerxes arrives at the pass with his vanguard and fleet and finds the Greeks already there.
It takes 5 days of bluff and bluster for the bulk of the army to arrive and re-victual the fleet.
During this time Persian light troops re-conoitre the mountains, remember large areas or the Empire are mountainous.
On the 6th day light troops are sent to probe the Greek defences and 200 ships sent to outflank the Greeks and bottle them up. The assaults fail with light casualties.
Day 2 the Persians assemble a force to outflank the greeks, unknown to all the 200 ships have been lost in a storm with 40,000 men approx. It won't be until day 3 that the flanking forces will be in place so Xerxes launches heavy infantry to pin the Greeks, unfortuneately they are outclassed and suffer moderate losse for no gain.
Day 3 the Greeks learn that the Persians have brushed aside the Phocians and will flank them, hastily they pull out and leave a sacrificial rearguard of 300 Spartans, 700 Thespians, 300 Thebans and 900 helots, The fleet no getting the worst of it and serving no purpose withdraws.
The Persians annihilate the rearguard, unluckily for them they just miss the bulk of the army, and their lost fleet can't stop the Greek fleet.
Net result the Persians have forced the pass, 2,200 greeks and a king are dead their own losses on land are probably not much different but theve lost 200 ships and their crews and through bad luck will of the Gods missed out on a crushing victory.
It is in the final part that the real effect is on the Greeks.