Expanding on Petrosian's Exchange Sacrifice, the positional exchange sacrifice has been honed into a routine weapon since Petrosian's heyday, 40-50 years ago. I ran into a nice example yesterday.
Marc Geenen is an ICCF GM who qualified for the 22nd ICCF World Championship by winning a strong candidate section. He annotated the following game from that event in L'Echiquier Belge, October 2007. In the diagrammed position White has just sacrificed a Pawn. Geenen noted:
White obtains compensation since it is not easy for me to develop the Queenside. Since we are approaching the endgame, White has just decided to centralize the King in order to join the Rooks. Considering the continuation of the game, it was probably preferable to castle. How to liberate the Black Queenside? Certainly 16...Na6 is possible, but permits 17.Bxa6 bxa6 18.Nc5, while 16...Nd7 17.Bd5 does not solve all of the problems.
I was particularly satisfied with my solution, even more because it wasn't suggested by any analysis engine. At first glance impossible, the move is a prelude to an excellent positional sacrifice.
The possibility of 17.Bd5 makes the text look like a blunder.
ICCF CT XXIV/1
[FEN "rnb2rk1/ppB1ppbp/6p1/7n/2B1N3/4P3/P2NKPPP/1R5R b - - 0 16"]
The game continued 17.Bd5 Ba6+ 18.Kf3. Geenen: 'Forced, because 18.Kd1 can be answered with 18...Nc6 19.Bxc6 Rac8. 18...Nd7. Geenen: 'More convincing than 18...Nc6?! 19.Rhc1 Rac8 20.Rxc6 Bb7 21.Rbc1 which leads to enormous complications.'
19.Bxa8 Rxa8 20.g4 Geenen: 'Other moves leave the White King without a safe haven.' 20...f5 21.gxh5 fxe4+ 22.Kg2 gxh5. Geenen summed up the position this way:
Now Black has the advantage. There are not only two Pawns for the exchange, but also several very strong pieces. In particular there is an excellent Bishop pair that assures positional domination, as demonstrated by the following moves.
The game continued 23.Nb3 Rc8 24.Rbc1 Bb2 25.Rc2 Ba3 26.Nd4 Nc5 27.Bg3 Bd3 28.Rd2 Kf7, and Black won in 59 moves.